257640851 has 4 divisors (see below), whose sum is σ = 277459392. Its totient is φ = 237822312.

The previous prime is 257640841. The next prime is 257640941. The reversal of 257640851 is 158046752.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 257640851 - 2¹⁸ = 257378707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257640811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9909251 + ... + 9909276.

It is an arithmetic number, because the mean of its divisors is an integer number (69364848).

Almost surely, 2^257640851 is an apocalyptic number.

257640851 is a deficient number, since it is larger than the sum of its proper divisors (19818541).

257640851 is a wasteful number, since it uses less digits than its factorization.

257640851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19818540.

The product of its (nonzero) digits is 67200, while the sum is 38.

The square root of 257640851 is about 16051.1946907388. The cubic root of 257640851 is about 636.3141412841.

The spelling of 257640851 in words is "two hundred fifty-seven million, six hundred forty thousand, eight hundred fifty-one".