21517654656 has 64 divisors (see below), whose sum is σ = 57174778080. Its totient is φ = 7170229248.

The previous prime is 21517654607. The next prime is 21517654661. The reversal of 21517654656 is 65645671512.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1508550 + ... + 1522746.

Almost surely, 2^21517654656 is an apocalyptic number.

It is an amenable number.

21517654656 is an abundant number, since it is smaller than the sum of its proper divisors (35657123424).

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

21517654656 is a wasteful number, since it uses less digits than its factorization.

21517654656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18161 (or 18149 counting only the distinct ones).

The product of its digits is 1512000, while the sum is 48.

The spelling of 21517654656 in words is "twenty-one billion, five hundred seventeen million, six hundred fifty-four thousand, six hundred fifty-six".