51 (number)
51 is the natural number
Natural number
In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...

 51 following 50
50 (number)
This article discusses the number fifty. For the year 50 CE, see 50. For other uses of 50, see 50 50 is the natural number following 49 and preceding 51.-In mathematics:...

 and preceding 52
52 (number)
52 is the natural number following 51 and preceding 53.-In mathematics:Fifty-two is the 6th Bell number and a decagonal number...


In mathematics

Fifty-one is the 14th discrete biprime and the 5th in the {3.q} semiprime
In mathematics, a semiprime is a natural number that is the product of two prime numbers. The first few semiprimes are 4, 6, 9, 10, 14, 15, 21, 22, 25, 26, ... ....

 family having the prime factors (3.17). The aliquot sum of 51 is 21, itself a discrete biprime. 51 is the 4th member of the 11-aliquot tree with the sequence (51, 21, 11, 1, 0).

51 is a pentagonal number
Pentagonal number
A pentagonal number is a figurate number that extends the concept of triangular and square numbers to the pentagon, but, unlike the first two, the patterns involved in the construction of pentagonal numbers are not rotationally symmetrical...

 as well as a centered pentagonal number
Centered pentagonal number
A centered pentagonal number is a centered figurate number that represents a pentagon with a dot in the center and all other dots surrounding the center in successive pentagonal layers...

 (one of the few numbers to be both) and an 18-gonal number and a Perrin number
Perrin number
In mathematics, the Perrin numbers are defined by the recurrence relationandThe sequence of Perrin numbers starts withThe number of different maximal independent sets in an n-vertex cycle graph is counted by the nth Perrin number.-History:...

. It is also the 6th Motzkin number
Motzkin number
In mathematics, a Motzkin number for a given number n is the number of different ways of drawing non-intersecting chords on a circle between n points. The Motzkin numbers have very diverse applications in geometry, combinatorics and number theory...

, telling the number of ways to draw non-intersecting chords
Chord (geometry)
A chord of a circle is a geometric line segment whose endpoints both lie on the circumference of the circle.A secant or a secant line is the line extension of a chord. More generally, a chord is a line segment joining two points on any curve, such as but not limited to an ellipse...

 between any six points on a circle's boundary, no matter where the points may be located on the boundary.

Since the greatest prime factor of 512 + 1 = 2602 is 1301, which is clearly more than 51 twice, 51 is a Størmer number
Størmer number
In mathematics, a Størmer number or arc-cotangent irreducible number, named after Carl Størmer, is a positive integer n for which the greatest prime factor of n2 + 1 meets or exceeds 2n. The first few Størmer numbers are 1, 2, 4, 5, 6, 9, 10, 11, 12, 14, 15, 16, 19, 20, etc....



  • Messier object
    Messier object
    The Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771. The original motivation of the catalogue was that Messier was a comet hunter, and was frustrated by objects which resembled but were not comets...

    M51 or M-51 may refer to:* M-51 , a state highway in Michigan* M51 SLBM, a French nuclear ballistic missile* BMW M51, a 1991 straight-6 Diesel engine* Eidgenössischer Stutzer 1851, a historical service rifle of the Swiss Army...

    , a magnitude 8.0 spiral galaxy
    Spiral galaxy
    A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...

     in the constellation
    In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

     Canes Venatici
    Canes Venatici
    Canes Venatici is one of the 88 official modern constellations. It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for "hunting dogs", and the constellation is often depicted in illustrations as representing the dogs of Boötes the...

    , also known as the Whirlpool Galaxy
    Whirlpool Galaxy
    The Whirlpool Galaxy is an interacting grand-design spiral galaxy that is estimated to be 23 ± 4 million light-years from the Milky Way Galaxy. in the constellation Canes Venatici...

  • The New General Catalogue
    New General Catalogue
    The New General Catalogue of Nebulae and Clusters of Stars is a well-known catalogue of deep sky objects in astronomy. It contains 7,840 objects, known as the NGC objects...

     object NGC 51, a spiral galaxy
    Spiral galaxy
    A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...

     in the constellation Andromeda
    Andromeda (constellation)
    Andromeda is a constellation in the northern sky. It is named after Andromeda, the princess in the Greek legend of Perseus who was chained to a rock to be eaten by the sea monster Cetus...

  • The Saros number of the solar eclipse
    Solar eclipse
    As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon, when the Sun and the Moon are in conjunction as seen from Earth. At least...

     series which began on -1407 September 2 and ended on +108 February 29. The duration of Saros series 51 was 1514.5 years, and it contained 85 solar eclipses. The Saros number of the lunar eclipse
    Lunar eclipse
    A lunar eclipse occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a...

     series which began on -1105 June 13 and ended on +193 July 31. The duration of Saros series 51 was 1298.1 years, and it contained 73 lunar eclipses.

In sports

  • Las Vegas 51s
    Las Vegas 51s
    The Las Vegas 51s, formerly known as the Las Vegas Stars, are a minor league baseball team. They are the Triple-A affiliate of the Toronto Blue Jays. They play at Cashman Field in Las Vegas, Nevada. The team competes in the Pacific Coast League...

    , a minor league baseball team of the Pacific Coast League
  • The jersey number
    Squad number
    In team sports, the squad number, shirt number, jersey number, sweater number, uniform number or simply a number is the number worn on a player's uniform, to identify and distinguish each player from others wearing the same or similar uniforms...

     51 has been retired by a number of North American sports teams in honor of past playing greats.
    • In the National Football League
      National Football League
      The National Football League is the highest level of professional American football in the United States, and is considered the top professional American football league in the world. It was formed by eleven teams in 1920 as the American Professional Football Association, with the league changing...

      • The Carolina Panthers
        Carolina Panthers
        The Carolina Panthers are a professional American football team based in Charlotte, North Carolina. They are currently members of the South Division of the National Football Conference in the National Football League . The Panthers, along with the Jacksonville Jaguars, joined the NFL as expansion...

        , for Sam Mills
        Sam Mills
        Samuel Davis "Sam" Mills, Jr. was an American football linebacker who played twelve seasons in the National Football League for the New Orleans Saints and Carolina Panthers.-Early life:...

      • The Chicago Bears
        Chicago Bears
        The Chicago Bears are a professional American football team based in Chicago, Illinois. They are members of the North Division of the National Football Conference in the National Football League...

        , for Hall of Famer
        Pro Football Hall of Fame
        The Pro Football Hall of Fame is the hall of fame of professional football in the United States with an emphasis on the National Football League . It opened in Canton, Ohio, on September 7, 1963, with 17 charter inductees...

         Dick Butkus
        Dick Butkus
        Richard Marvin "Dick" Butkus is a former American football player for the Chicago Bears. He was drafted in 1965 and he is also widely regarded as one of the best and most durable linebackers of all time. Butkus starred as a football player for the University of Illinois and the Chicago Bears. He...

    • In Major League Baseball
      Major League Baseball
      Major League Baseball is the highest level of professional baseball in the United States and Canada, consisting of teams that play in the National League and the American League...

      • The San Diego Padres
        San Diego Padres
        The San Diego Padres are a Major League Baseball team based in San Diego, California. They play in the National League Western Division. Founded in 1969, the Padres have won the National League Pennant twice, in 1984 and 1998, losing in the World Series both times...

        , for Trevor Hoffman
        Trevor Hoffman
        Trevor William Hoffman is a former Major League Baseball right-handed relief pitcher. During his 18-year career from 1993 to 2010, he pitched for the Florida Marlins, San Diego Padres, and the Milwaukee Brewers, spending years of his career with the Padres. A long-time closer, he is the Major...


In other fields

Fifty-one is:
  • The code for international direct dial phone calls to Peru
    Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

  • The model number of the P-51 Mustang
    P-51 Mustang
    The North American Aviation P-51 Mustang was an American long-range, single-seat fighter and fighter-bomber used during World War II, the Korean War and in several other conflicts...

     WWII fighter aircraft
  • Area 51
    Area 51
    Area 51 is a military base, and a remote detachment of Edwards Air Force Base. It is located in the southern portion of Nevada in the western United States, 83 miles north-northwest of downtown Las Vegas. Situated at its center, on the southern shore of Groom Lake, is a large military airfield...

    , a parcel of U.S. military-controlled land in southern Nevada
    Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

    , apparently containing a secret aircraft testing facility
  • Part of the title of a collection of stories by Lord Dunsany
    Edward Plunkett, 18th Baron Dunsany
    Edward John Moreton Drax Plunkett, 18th Baron of Dunsany was an Irish writer and dramatist, notable for his work, mostly in fantasy, published under the name Lord Dunsany...

    , Fifty-One Tales
    Fifty-One Tales
    Fifty-One Tales is a collection of fantasy short stories by Irish writer Lord Dunsany, considered a major influence on the work of J. R. R. Tolkien, H. P. Lovecraft, Ursula K. Le Guin and others. The first editions, in hardcover, were published simultaneously in London and New York by Elkin Mathews...

  • Washington D.C. and Puerto Rico
    Puerto Rico
    Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...

     often mentioned as the future "51st State
    51st state
    The 51st state, in United States political discourse, is a phrase that refers to areas either seriously or derisively considered candidates for addition to the 50 states already part of the United States. Before 1959, when Alaska and Hawaii joined the U.S., the term "the 49th state" was used...

  • "51st anniversary" song by Jimi Hendrix
    Jimi Hendrix
    James Marshall "Jimi" Hendrix was an American guitarist and singer-songwriter...

  • "Come in Number 51, Your Time is Up" song by Pink Floyd
    Pink Floyd
    Pink Floyd were an English rock band that achieved worldwide success with their progressive and psychedelic rock music. Their work is marked by the use of philosophical lyrics, sonic experimentation, innovative album art, and elaborate live shows. Pink Floyd are one of the most commercially...

  • "Number 51" is referenced in the song "The Happening," by The Pixies
  • Bob Dylan
    Bob Dylan
    Bob Dylan is an American singer-songwriter, musician, poet, film director and painter. He has been a major and profoundly influential figure in popular music and culture for five decades. Much of his most celebrated work dates from the 1960s when he was an informal chronicler and a seemingly...

    : Highway 51 Blues and the name of a band
  • The Parker 51
    Parker 51
    The Parker 51, introduced in 1941, is a famous fountain pen. Parker’s period advertising called it “The World’s Most Wanted Pen,” and this assertion was true although a little deceptive; the U.S.A. entered World War II in December 1941, and the War Production Board placed severe restrictions on...

    , introduced in 1941, may well be the most famous fountain pen
    Fountain pen
    A fountain pen is a nib pen that, unlike its predecessor the dip pen, contains an internal reservoir of water-based liquid ink. The pen draws ink from the reservoir through a feed to the nib and deposits it on paper via a combination of gravity and capillary action...

     ever made
  • A brand of pastis
    Pastis is an anise-flavored liqueur and apéritif from France, typically containing 40–45% alcohol by volume, although alcohol-free varieties exist.-Origins:...

     (anise liqueur) manufactured by Pernod Ricard
    Pernod Ricard
    Pernod Ricard is a French company that produces distilled beverages. The company's eponymous products, Pernod Anise and Ricard Pastis, are both anise-flavoured liqueurs and are often referred to simply as Pernod or Ricard...

  • Pixar's
    Pixar Animation Studios, pronounced , is an American computer animation film studio based in Emeryville, California. The studio has earned 26 Academy Awards, seven Golden Globes, and three Grammy Awards, among many other awards and acknowledgments. Its films have made over $6.3 billion worldwide...

     film Cars
    Cars (film)
    Cars is a 2006 American animated family film produced by Pixar and directed by John Lasseter and co-directed by Joe Ranft. It is the seventh Disney·Pixar feature film, and Pixar's final, independently-produced motion picture before its purchase by Disney...

    tells about a rookie racecar, Lightning McQueen who crashes into Radiator Springs, a town on Highway 66
    U.S. Route 66
    U.S. Route 66 was a highway within the U.S. Highway System. One of the original U.S. highways, Route 66 was established on November 11, 1926 -- with road signs erected the following year...

    . There, he meets the town's doctor & judge, Doc Hudson, a royal blue
    Royal blue
    Royal blue describes both a bright shade and a dark shade of azure blue. It is said to have been invented by millers in Rode, Somerset, a consortium of which won a competition to make a dress for the British queen, Charlotte of Mecklenburg-Strelitz....

     1951 Hudson Hornet
    Hudson Hornet
    The Hudson Hornet is an automobile that was produced by the Hudson Motor Car Company of Detroit, Michigan between 1951 and 1954. The Hornet was also built by American Motors Corporation in Kenosha, Wisconsin and marketed under the Hudson brand between 1955 and 1957.The first-generation Hudson...

    . Later, he (Doc) turns out to be a retired racecar himself. (Fabulous Hudson Hornet
    Fabulous Hudson Hornet
    The Fabulous Hudson Hornet was a famous NASCAR Grand National and AAA stock car produced by the Hudson Motor Car Company. Marshall Teague and Herb Thomas each drove in a Hudson Hornet that they nicknamed the "Fabulous Hudson Hornet"....

    ). As a racecar, his racing number was 51. 51 is also on Doc's licence plate (51HHMD).
  • "Cachaça 51" is the brand name of a cachaça produced by a Companhia Müller de Bebidas in Pirassununga
    Pirassununga is a municipality in the state of São Paulo in Brazil. The population in 2010 was 70.081 and the area is 728.78 km². The elevation is 627 m. This place name comes from the Tupi language....

    , São Paulo
    São Paulo
    São Paulo is the largest city in Brazil, the largest city in the southern hemisphere and South America, and the world's seventh largest city by population. The metropolis is anchor to the São Paulo metropolitan area, ranked as the second-most populous metropolitan area in the Americas and among...

    , Brasil.
  • The '51
    Squier '51
    The Squier '51 was an electric guitar made by Squier, a subsidiary of Fender. The '51 is notable for being one of the few original designs made by Squier, which normally manufactures less expensive authorized copies of Fender's popular guitars and bass guitars....

     is a guitar made by Fender
    Fender Musical Instruments Corporation, commonly referred to as simply Fender, of Scottsdale, Arizona is a manufacturer of stringed instruments and amplifiers, such as solid-body electric guitars, including the Stratocaster and the Telecaster...

    's second brand, Squier
    Squier is a musical instrument brand name owned by the Fender Musical Instruments Corporation.-History:Fender, under the ownership of CBS, acquired the Squier brand name in 1965 when it bought a USA based string making firm , but it lay dormant for many years...

    . It is notable for being one of only a few original models produced by the marque.
  • The number of the French department Marne
    Marne is a department in north-eastern France named after the river Marne which flows through the department. The prefecture of Marne is Châlons-en-Champagne...

  • Suda51 is the nickname of Goichi Suda, the CEO of Grasshopper Manufacturer.
  • Year identifier used on motor vehicles registered in the UK between 1 September 2001 and 28 February 2002
  • The station number and apparatus numbers from the TV series Emergency!
    Emergency! is an American television series that combines the medical drama and action-adventure genres. It was produced by Mark VII Limited and distributed by Universal Studios...

  • 51 (film)
    51 (film)
    51 is an American horror film, which was directed by Jason Connery and starring Bruce Boxleitner and John Shea.-Plot:Political and public pressure coerces the government into allowing two well-known reporters and their assistants limited access to the ultra-secretive Area 51...

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