21655602660 has 96 divisors (see below), whose sum is σ = 64244783232. Its totient is φ = 5431552000.

The previous prime is 21655602601. The next prime is 21655602707. The reversal of 21655602660 is 6620655612.

It is a happy 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, 1761535 + ... + 1773785.

It is an arithmetic number, because the mean of its divisors is an integer number (669216492).

Almost surely, 2^21655602660 is an apocalyptic number.

21655602660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21655602660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32122391616).

21655602660 is an abundant number, since it is smaller than the sum of its proper divisors (42589180572).

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

21655602660 is a wasteful number, since it uses less digits than its factorization.

21655602660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14013 (or 14011 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 39.

The spelling of 21655602660 in words is "twenty-one billion, six hundred fifty-five million, six hundred two thousand, six hundred sixty".