21657156056 has 16 divisors (see below), whose sum is σ = 41551521000. Its totient is φ = 10576750464.

The previous prime is 21657156041. The next prime is 21657156067. The reversal of 21657156056 is 65065175612.

It is a junction number, because it is equal to n+sod(n) for n = 21657155998 and 21657156016.

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, 31478081 + ... + 31478768.

Almost surely, 2^21657156056 is an apocalyptic number.

It is an amenable number.

21657156056 is a deficient number, since it is larger than the sum of its proper divisors (19894364944).

21657156056 is a wasteful number, since it uses less digits than its factorization.

21657156056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62956898 (or 62956894 counting only the distinct ones).

The product of its (nonzero) digits is 378000, while the sum is 44.

The spelling of 21657156056 in words is "twenty-one billion, six hundred fifty-seven million, one hundred fifty-six thousand, fifty-six".