21565856512 has 36 divisors (see below), whose sum is σ = 43070554800. Its totient is φ = 10777146368.

The previous prime is 21565856489. The next prime is 21565856531.

21565856512 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×21565856512² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 477333 + ... + 520555.

It is an arithmetic number, because the mean of its divisors is an integer number (1196404300).

Almost surely, 2^21565856512 is an apocalyptic number.

It is an amenable number.

21565856512 is a deficient number, since it is larger than the sum of its proper divisors (21504698288).

21565856512 is an equidigital number, since it uses as much as digits as its factorization.

21565856512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45188 (or 45174 counting only the distinct ones).

The product of its digits is 720000, while the sum is 46.

The spelling of 21565856512 in words is "twenty-one billion, five hundred sixty-five million, eight hundred fifty-six thousand, five hundred twelve".