A gigantic prime is a prime number

Prime number

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. A natural number greater than 1 that is not a prime number is called a composite number. For example 5 is prime, as only 1 and 5 divide it, whereas 6 is composite, since it has the divisors 2...

 with at least 10,000 decimal digits.

The term appeared in Journal of Recreational Mathematics

Journal of Recreational Mathematics

The Journal of Recreational Mathematics is an American journal dedicated to recreational mathematics, started in 1968. It is published quarterly by the Baywood Publishing Company....

 in the article "Collecting gigantic and titanic primes" (1992) by Samuel Yates

Samuel Yates

Samuel Yates was a mathematician who first described unique primes in the 1980s. In 1984 he began the list of "Largest Known Primes" and coined the name titanic prime for any prime with 1,000 or more decimal digits...

. Chris Caldwell, who continued Yates' collection in the prime pages

Prime pages

The Prime Pages is a website about prime numbers maintained by Chris Caldwell at the University of Tennessee at Martin.The site maintains the list of the "5,000 largest known primes", selected smaller primes of special forms, and many "top twenty" lists for primes of various forms...

, reports that he changed the requirement from Yates' original 5,000 digits to 10,000 digits, when he was asked to revise the article after the death of Yates. http://primes.utm.edu/references/refs.cgi?long=Yates92b Few primes of that size were known then, but a modern PC

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

 can find many in a day.

The first discovered gigantic prime was the Mersenne prime

Mersenne prime

In mathematics, a Mersenne number, named after Marin Mersenne , is a positive integer that is one less than a power of two: M_p=2^p-1.\,...

 2⁴⁴⁴⁹⁷ − 1. It has 13,395 digits and was found in 1979 by Harry Nelson

Harry Lewis Nelson

Harry Lewis Nelson is an American mathematician and computer programmer. He was a member of the team that won the World Computer Chess Championship in 1983 and 1986, and was a co-discoverer of the 27th Mersenne prime in 1979 . He also served as editor of the Journal of Recreational Mathematics for...

 and David Slowinski

David Slowinski

David Slowinski is a mathematician involved in prime numbers. His career highlights have included the discovery of several of the largest known Mersenne primes:1* 244497−1 on April 8 1979* 286243−1 on September 25 1982...

. http://primes.utm.edu/notes/by_year.html

The smallest gigantic prime is 10⁹⁹⁹⁹ + 33603. It was proved prime in 2003 by Jens Franke, Thorsten Kleinjung and Tobias Wirth with their own distributed ECPP

Elliptic curve primality proving

Elliptic Curve Primality Proving is a method based on elliptic curves to prove the primality of a number . It is a general-purpose algorithm, meaning it does not depend on the number being of a special form...

program. http://www.ellipsa.net/primo/ecpp10000.txt It was the largest ECPP proof at the time.