257491691 has 2 divisors, whose sum is σ = 257491692. Its totient is φ = 257491690.

The previous prime is 257491627. The next prime is 257491733. The reversal of 257491691 is 196194752.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 257491691 - 2⁶ = 257491627 is a prime.

It is not a weakly prime, because it can be changed into another prime (257491891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128745845 + 128745846.

It is an arithmetic number, because the mean of its divisors is an integer number (128745846).

Almost surely, 2^257491691 is an apocalyptic number.

257491691 is a deficient number, since it is larger than the sum of its proper divisors (1).

257491691 is an equidigital number, since it uses as much as digits as its factorization.

257491691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 136080, while the sum is 44.

The square root of 257491691 is about 16046.5476349276. The cubic root of 257491691 is about 636.1913205186.

The spelling of 257491691 in words is "two hundred fifty-seven million, four hundred ninety-one thousand, six hundred ninety-one".