251978591 has 2 divisors, whose sum is σ = 251978592. Its totient is φ = 251978590.

The previous prime is 251978569. The next prime is 251978599. The reversal of 251978591 is 195879152.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 251978591 - 2⁶ = 251978527 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251978599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125989295 + 125989296.

It is an arithmetic number, because the mean of its divisors is an integer number (125989296).

Almost surely, 2^251978591 is an apocalyptic number.

251978591 is a deficient number, since it is larger than the sum of its proper divisors (1).

251978591 is an equidigital number, since it uses as much as digits as its factorization.

251978591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 226800, while the sum is 47.

The square root of 251978591 is about 15873.8335319481. The cubic root of 251978591 is about 631.6180720973.

The spelling of 251978591 in words is "two hundred fifty-one million, nine hundred seventy-eight thousand, five hundred ninety-one".