21056172504 has 16 divisors (see below), whose sum is σ = 52640431320. Its totient is φ = 7018724160.

The previous prime is 21056172499. The next prime is 21056172517. The reversal of 21056172504 is 40527165012.

It is a congruent number.

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, 438670237 + ... + 438670284.

Almost surely, 2^21056172504 is an apocalyptic number.

21056172504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21056172504 is an abundant number, since it is smaller than the sum of its proper divisors (31584258816).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21056172504 is a wasteful number, since it uses less digits than its factorization.

21056172504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 877340530 (or 877340526 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 33.

The spelling of 21056172504 in words is "twenty-one billion, fifty-six million, one hundred seventy-two thousand, five hundred four".