21655212566616 has 96 divisors (see below), whose sum is σ = 59512848314400. Its totient is φ = 7112277527040.

The previous prime is 21655212566591. The next prime is 21655212566623. The reversal of 21655212566616 is 61666521255612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6837580 + ... + 9490148.

It is an arithmetic number, because the mean of its divisors is an integer number (619925503275).

Almost surely, 2^{21655212566616} 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 21655212566616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29756424157200).

21655212566616 is an abundant number, since it is smaller than the sum of its proper divisors (37857635747784).

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

21655212566616 is a wasteful number, since it uses less digits than its factorization.

21655212566616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2654249 (or 2654242 counting only the distinct ones).

The product of its digits is 7776000, while the sum is 54.

The spelling of 21655212566616 in words is "twenty-one trillion, six hundred fifty-five billion, two hundred twelve million, five hundred sixty-six thousand, six hundred sixteen".