256621409679 has 16 divisors (see below), whose sum is σ = 346360234752. Its totient is φ = 168982666368.

The previous prime is 256621409633. The next prime is 256621409719. The reversal of 256621409679 is 976904126652.

It is not a de Polignac number, because 256621409679 - 2¹⁵ = 256621376911 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256621409879) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1048942 + ... + 1270244.

It is an arithmetic number, because the mean of its divisors is an integer number (21647514672).

Almost surely, 2^256621409679 is an apocalyptic number.

256621409679 is a deficient number, since it is larger than the sum of its proper divisors (89738825073).

256621409679 is a wasteful number, since it uses less digits than its factorization.

256621409679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226046.

The product of its (nonzero) digits is 9797760, while the sum is 57.

It can be divided in two parts, 25662 and 1409679, that added together give a palindrome (1435341).

The spelling of 256621409679 in words is "two hundred fifty-six billion, six hundred twenty-one million, four hundred nine thousand, six hundred seventy-nine".