256740857 has 8 divisors (see below), whose sum is σ = 267381000. Its totient is φ = 246219904.

The previous prime is 256740839. The next prime is 256740929. The reversal of 256740857 is 758047652.

It can be written as a sum of positive squares in 4 ways, for example, as 26429881 + 230310976 = 5141^2 + 15176^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 256740857 - 2¹⁴ = 256724473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256740257) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25388 + ... + 34029.

It is an arithmetic number, because the mean of its divisors is an integer number (33422625).

Almost surely, 2^256740857 is an apocalyptic number.

It is an amenable number.

256740857 is a deficient number, since it is larger than the sum of its proper divisors (10640143).

256740857 is a wasteful number, since it uses less digits than its factorization.

256740857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59595.

The product of its (nonzero) digits is 470400, while the sum is 44.

The square root of 256740857 is about 16023.1350552880. The cubic root of 256740857 is about 635.5723502292.

The spelling of 256740857 in words is "two hundred fifty-six million, seven hundred forty thousand, eight hundred fifty-seven".