256879917 has 56 divisors (see below), whose sum is σ = 446993280. Its totient is φ = 144516960.

The previous prime is 256879897. The next prime is 256879921. The reversal of 256879917 is 719978652.

256879917 is a `hidden beast` number, since 2 + 568 + 79 + 9 + 1 + 7 = 666.

It is not a de Polignac number, because 256879917 - 2⁶ = 256879853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256879927) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 361959 + ... + 362667.

Almost surely, 2^256879917 is an apocalyptic number.

256879917 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

256879917 is a deficient number, since it is larger than the sum of its proper divisors (190113363).

256879917 is an frugal number, since it uses more digits than its factorization.

256879917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805 (or 790 counting only the distinct ones).

The product of its digits is 1905120, while the sum is 54.

The square root of 256879917 is about 16027.4738184157. The cubic root of 256879917 is about 635.6870790648.

The spelling of 256879917 in words is "two hundred fifty-six million, eight hundred seventy-nine thousand, nine hundred seventeen".