256802391 has 24 divisors (see below), whose sum is σ = 393376464. Its totient is φ = 160876800.

The previous prime is 256802387. The next prime is 256802401. The reversal of 256802391 is 193208652.

256802391 is a `hidden beast` number, since 2 + 568 + 0 + 2 + 3 + 91 = 666.

It is not a de Polignac number, because 256802391 - 2² = 256802387 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256802191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 160005 + ... + 161601.

It is an arithmetic number, because the mean of its divisors is an integer number (16390686).

Almost surely, 2^256802391 is an apocalyptic number.

256802391 is a deficient number, since it is larger than the sum of its proper divisors (136574073).

256802391 is a wasteful number, since it uses less digits than its factorization.

256802391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2671 (or 2668 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 256802391 is about 16025.0551013093. The cubic root of 256802391 is about 635.6231228064.

The spelling of 256802391 in words is "two hundred fifty-six million, eight hundred two thousand, three hundred ninety-one".