256659868517442 has 16 divisors (see below), whose sum is σ = 552805870653120. Its totient is φ = 78972267236112.

The previous prime is 256659868517407. The next prime is 256659868517449. The reversal of 256659868517442 is 244715868956652.

It is a Harshad number since it is a multiple of its sum of digits (78), and also a Moran number because the ratio is a prime number: 3290511134839 = 256659868517442 / (2 + 5 + 6 + 6 + 5 + 9 + 8 + 6 + 8 + 5 + 1 + 7 + 4 + 4 + 2).

It is not an unprimeable number, because it can be changed into a prime (256659868517449) 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 7 ways as a sum of consecutive naturals, for example, 1645255567342 + ... + 1645255567497.

It is an arithmetic number, because the mean of its divisors is an integer number (34550366915820).

Almost surely, 2^{256659868517442} is an apocalyptic number.

256659868517442 is an abundant number, since it is smaller than the sum of its proper divisors (296146002135678).

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

256659868517442 is a wasteful number, since it uses less digits than its factorization.

256659868517442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3290511134857.

The product of its digits is 6967296000, while the sum is 78.

The spelling of 256659868517442 in words is "two hundred fifty-six trillion, six hundred fifty-nine billion, eight hundred sixty-eight million, five hundred seventeen thousand, four hundred forty-two".