251 (number) - Alchetron, The Free Social Encyclopedia

251 252 → Factorization 251 Roman numeral CCLI		Cardinal two hundred fifty-one Prime 54th
Ordinal 251st(two hundred and fifty-first)

251 (two hundred [and] fifty-one) is the natural number between 250 and 252. It is also a prime number.

In mathematics

251 is:

a Sophie Germain prime.

the sum of three consecutive primes (79 + 83 + 89) and seven consecutive primes (23 + 29 + 31 + 37 + 41 + 43 + 47).

an Eisenstein prime with no imaginary part.

a de Polignac number, meaning that it is odd and cannot be formed by adding a power of two to a prime number.

the smallest number that can be formed in more than one way by summing three positive cubes:

251 = 2 3 + 3 3 + 6 3 = 1 3 + 5 3 + 5 3 .

Every 5 × 5 matrix has exactly 251 square submatrices.

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