256697856 has 160 divisors (see below), whose sum is σ = 785664000. Its totient is φ = 82667520.

The previous prime is 256697827. The next prime is 256697867. The reversal of 256697856 is 658796652.

It is a happy number.

256697856 is a `hidden beast` number, since 2 + 566 + 9 + 78 + 5 + 6 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 428245 + ... + 428843.

It is an arithmetic number, because the mean of its divisors is an integer number (4910400).

Almost surely, 2^256697856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256697856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (392832000).

256697856 is an abundant number, since it is smaller than the sum of its proper divisors (528966144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256697856 is an equidigital number, since it uses as much as digits as its factorization.

256697856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 657 (or 635 counting only the distinct ones).

The product of its digits is 5443200, while the sum is 54.

The square root of 256697856 is about 16021.7931580707. The cubic root of 256697856 is about 635.5368646778.

The spelling of 256697856 in words is "two hundred fifty-six million, six hundred ninety-seven thousand, eight hundred fifty-six".