21263521256 has 16 divisors (see below), whose sum is σ = 42214343940. Its totient is φ = 10006362880.

The previous prime is 21263521219. The next prime is 21263521283. The reversal of 21263521256 is 65212536212.

It can be written as a sum of positive squares in 2 ways, for example, as 21254724100 + 8797156 = 145790^2 + 2966^2 .

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, 78174575 + ... + 78174846.

Almost surely, 2^21263521256 is an apocalyptic number.

It is an amenable number.

21263521256 is a deficient number, since it is larger than the sum of its proper divisors (20950822684).

21263521256 is a wasteful number, since it uses less digits than its factorization.

21263521256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156349444 (or 156349440 counting only the distinct ones).

The product of its digits is 43200, while the sum is 35.

The spelling of 21263521256 in words is "twenty-one billion, two hundred sixty-three million, five hundred twenty-one thousand, two hundred fifty-six".