21663603120564 has 96 divisors (see below), whose sum is σ = 56531984902400. Its totient is φ = 7174019249280.

The previous prime is 21663603120557. The next prime is 21663603120581. The reversal of 21663603120564 is 46502130636612.

21663603120564 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 3 + 60 + 3 + 1 + 20 + 564 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 105516369 + ... + 105721479.

Almost surely, 2^{21663603120564} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21663603120564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28265992451200).

21663603120564 is an abundant number, since it is smaller than the sum of its proper divisors (34868381781836).

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

21663603120564 is a wasteful number, since it uses less digits than its factorization.

21663603120564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211510 (or 211502 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 45.

The spelling of 21663603120564 in words is "twenty-one trillion, six hundred sixty-three billion, six hundred three million, one hundred twenty thousand, five hundred sixty-four".