257665813 has 2 divisors, whose sum is σ = 257665814. Its totient is φ = 257665812.

The previous prime is 257665801. The next prime is 257665823. The reversal of 257665813 is 318566752.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 132181009 + 125484804 = 11497^2 + 11202^2 .

It is a cyclic number.

It is not a de Polignac number, because 257665813 - 2⁹ = 257665301 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 257665813.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257665823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128832906 + 128832907.

It is an arithmetic number, because the mean of its divisors is an integer number (128832907).

Almost surely, 2^257665813 is an apocalyptic number.

It is an amenable number.

257665813 is a deficient number, since it is larger than the sum of its proper divisors (1).

257665813 is an equidigital number, since it uses as much as digits as its factorization.

257665813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 302400, while the sum is 43.

The square root of 257665813 is about 16051.9722464250. The cubic root of 257665813 is about 636.3346907694.

The spelling of 257665813 in words is "two hundred fifty-seven million, six hundred sixty-five thousand, eight hundred thirteen".