257409991 has 2 divisors, whose sum is σ = 257409992. Its totient is φ = 257409990.

The previous prime is 257409989. The next prime is 257410001. The reversal of 257409991 is 199904752.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 257409991 - 2¹ = 257409989 is a prime.

Together with 257409989, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257409941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128704995 + 128704996.

It is an arithmetic number, because the mean of its divisors is an integer number (128704996).

Almost surely, 2^257409991 is an apocalyptic number.

257409991 is a deficient number, since it is larger than the sum of its proper divisors (1).

257409991 is an equidigital number, since it uses as much as digits as its factorization.

257409991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 204120, while the sum is 46.

The square root of 257409991 is about 16044.0017140363. The cubic root of 257409991 is about 636.1240273062.

The spelling of 257409991 in words is "two hundred fifty-seven million, four hundred nine thousand, nine hundred ninety-one".