21665233556 has 12 divisors (see below), whose sum is σ = 37917511968. Its totient is φ = 10831658712.

The previous prime is 21665233529. The next prime is 21665233589. The reversal of 21665233556 is 65533256612.

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, 187376 + ... + 280071.

It is an arithmetic number, because the mean of its divisors is an integer number (3159792664).

Almost surely, 2^21665233556 is an apocalyptic number.

It is an amenable number.

21665233556 is a deficient number, since it is larger than the sum of its proper divisors (16252278412).

21665233556 is a wasteful number, since it uses less digits than its factorization.

21665233556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 479038 (or 479036 counting only the distinct ones).

The product of its digits is 972000, while the sum is 44.

The spelling of 21665233556 in words is "twenty-one billion, six hundred sixty-five million, two hundred thirty-three thousand, five hundred fifty-six".