251 (number)

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

In mathematics
251 is: Every 5 &times; 5 matrix has exactly 251 square submatrices.
 * a Sophie Germain prime.
 * the sum of three consecutive primes (79 + 83 + 89) and seven consecutive primes (23 + 29 + 31 + 37 + 41 + 43 + 47).
 * a Chen prime.
 * 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: $$251 = 2^3 + 3^3 + 6^3 = 1^3 + 5^3 + 5^3.$$