257651987 has 2 divisors, whose sum is σ = 257651988. Its totient is φ = 257651986.

The previous prime is 257651963. The next prime is 257652007. The reversal of 257651987 is 789156752.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 257651987 - 2⁶ = 257651923 is a prime.

It is not a weakly prime, because it can be changed into another prime (257651087) 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, 128825993 + 128825994.

It is an arithmetic number, because the mean of its divisors is an integer number (128825994).

Almost surely, 2^257651987 is an apocalyptic number.

257651987 is a deficient number, since it is larger than the sum of its proper divisors (1).

257651987 is an equidigital number, since it uses as much as digits as its factorization.

257651987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1058400, while the sum is 50.

The square root of 257651987 is about 16051.5415770573. The cubic root of 257651987 is about 636.3233089454.

The spelling of 257651987 in words is "two hundred fifty-seven million, six hundred fifty-one thousand, nine hundred eighty-seven".