256611575853821 has 16 divisors (see below), whose sum is σ = 273235988995200. Its totient is φ = 240300687052800.

The previous prime is 256611575853671. The next prime is 256611575853937. The reversal of 256611575853821 is 128358575116652.

It is a cyclic number.

It is not a de Polignac number, because 256611575853821 - 2¹⁸ = 256611575591677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256611572853821) 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, 17665220 + ... + 28727741.

It is an arithmetic number, because the mean of its divisors is an integer number (17077249312200).

Almost surely, 2^{256611575853821} is an apocalyptic number.

It is an amenable number.

256611575853821 is a deficient number, since it is larger than the sum of its proper divisors (16624413141379).

256611575853821 is a wasteful number, since it uses less digits than its factorization.

256611575853821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46396340.

The product of its digits is 120960000, while the sum is 65.

The spelling of 256611575853821 in words is "two hundred fifty-six trillion, six hundred eleven billion, five hundred seventy-five million, eight hundred fifty-three thousand, eight hundred twenty-one".