420 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...

 following 419 and preceding 421.

420 is the sum of four consecutive primes (101 + 103 + 107 + 109). 420 is a zero of the Mertens function and is sparsely totient.
It is a pronic number

Pronic number

A pronic number, oblong number, rectangular number or heteromecic number, is a number which is the product of two consecutive integers, that is, n . The n-th pronic number is twice the n-th triangular number and n more than the n-th square number...

, and the smallest number divisible by the numbers 1 to 7, and as a consequence of that it is a Harshad number

Harshad number

A Harshad number, or Niven number in a given number base, is an integer that is divisible by the sum of its digits when written in that base. Harshad numbers were defined by D. R. Kaprekar, a mathematician from India. The word "Harshad" comes from the Sanskrit + , meaning joy-giver. The Niven...

 in every base from 2 to 10 except base 5. It is a 141-gonal number

Polygonal number

In mathematics, a polygonal number is a number represented as dots or pebbles arranged in the shape of a regular polygon. The dots were thought of as alphas . These are one type of 2-dimensional figurate numbers.- Definition and examples :...

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420 is also associated with cannabis

420 (cannabis culture)

420, 4:20 or 4/20 refers to consumption of cannabis and, by extension, a way to identify oneself with cannabis subculture. The notable day for these is April 20.- Origins of terms :...

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420 also refers to a con-artist, trickster in India and Pakistan, see Section 420

Section 420

Section 420 of the Indian Penal Code also used in Pakistan, Bangladesh and Afghanistan has become a slang reference for a confidence trickster. Such criminals are called 420 in popular culture in those countries...

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