257809831 has 2 divisors, whose sum is σ = 257809832. Its totient is φ = 257809830.

The previous prime is 257809789. The next prime is 257809843. The reversal of 257809831 is 138908752.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 257809831 - 2¹⁵ = 257777063 is a prime.

It is a super-2 number, since 2×257809831² = 132931817920497122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257809891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128904915 + 128904916.

It is an arithmetic number, because the mean of its divisors is an integer number (128904916).

Almost surely, 2^257809831 is an apocalyptic number.

257809831 is a deficient number, since it is larger than the sum of its proper divisors (1).

257809831 is an equidigital number, since it uses as much as digits as its factorization.

257809831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120960, while the sum is 43.

The square root of 257809831 is about 16056.4576105690. The cubic root of 257809831 is about 636.4532249015.

The spelling of 257809831 in words is "two hundred fifty-seven million, eight hundred nine thousand, eight hundred thirty-one".