257665823 has 2 divisors, whose sum is σ = 257665824. Its totient is φ = 257665822.

The previous prime is 257665813. The next prime is 257665867. The reversal of 257665823 is 328566752.

It is an a-pointer prime, because the next prime (257665867) can be obtained adding 257665823 to its sum of digits (44).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 257665823 - 2²⁰ = 256617247 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257665813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128832911 + 128832912.

It is an arithmetic number, because the mean of its divisors is an integer number (128832912).

Almost surely, 2^257665823 is an apocalyptic number.

257665823 is a deficient number, since it is larger than the sum of its proper divisors (1).

257665823 is an equidigital number, since it uses as much as digits as its factorization.

257665823 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 604800, while the sum is 44.

The square root of 257665823 is about 16051.9725579132. The cubic root of 257665823 is about 636.3346990014.

The spelling of 257665823 in words is "two hundred fifty-seven million, six hundred sixty-five thousand, eight hundred twenty-three".