21657236572 has 6 divisors (see below), whose sum is σ = 37900164008. Its totient is φ = 10828618284.

The previous prime is 21657236551. The next prime is 21657236617. The reversal of 21657236572 is 27563275612.

It is a super-2 number, since 2×21657236572² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2707154568 + ... + 2707154575.

Almost surely, 2^21657236572 is an apocalyptic number.

It is an amenable number.

21657236572 is a deficient number, since it is larger than the sum of its proper divisors (16242927436).

21657236572 is a wasteful number, since it uses less digits than its factorization.

21657236572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5414309147 (or 5414309145 counting only the distinct ones).

The product of its digits is 1058400, while the sum is 46.

The spelling of 21657236572 in words is "twenty-one billion, six hundred fifty-seven million, two hundred thirty-six thousand, five hundred seventy-two".