256564817 has 8 divisors (see below), whose sum is σ = 259259040. Its totient is φ = 253884960.

The previous prime is 256564801. The next prime is 256564829. The reversal of 256564817 is 718465652.

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 256564817 - 2⁴ = 256564801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256564837) 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, 34373 + ... + 41165.

It is an arithmetic number, because the mean of its divisors is an integer number (32407380).

Almost surely, 2^256564817 is an apocalyptic number.

It is an amenable number.

256564817 is a deficient number, since it is larger than the sum of its proper divisors (2694223).

256564817 is a wasteful number, since it uses less digits than its factorization.

256564817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7183.

The product of its digits is 403200, while the sum is 44.

The square root of 256564817 is about 16017.6408063110. The cubic root of 256564817 is about 635.4270523077.

The spelling of 256564817 in words is "two hundred fifty-six million, five hundred sixty-four thousand, eight hundred seventeen".