251 (number)
# 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:

* 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:$251=2^{3}+3^{3}+6^{3}=1^{3}+5^{3}+5^{3}.$

Every 5 × 5 matrix has exactly 251 square submatrices.

