256621604721401 has 4 divisors (see below), whose sum is σ = 256636117073232. Its totient is φ = 256607092369572.

The previous prime is 256621604721359. The next prime is 256621604721451. The reversal of 256621604721401 is 104127406126652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256621604721401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256621604721451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7256149391 + ... + 7256184756.

It is an arithmetic number, because the mean of its divisors is an integer number (64159029268308).

Almost surely, 2^{256621604721401} is an apocalyptic number.

It is an amenable number.

256621604721401 is a deficient number, since it is larger than the sum of its proper divisors (14512351831).

256621604721401 is a wasteful number, since it uses less digits than its factorization.

256621604721401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14512351830.

The product of its (nonzero) digits is 967680, while the sum is 47.

The spelling of 256621604721401 in words is "two hundred fifty-six trillion, six hundred twenty-one billion, six hundred four million, seven hundred twenty-one thousand, four hundred one".