21108086656 has 64 divisors (see below), whose sum is σ = 42847429680. Its totient is φ = 10355724288.

The previous prime is 21108086641. The next prime is 21108086663. The reversal of 21108086656 is 65668080112.

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

It is a congruent number.

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, 1835035 + ... + 1846501.

Almost surely, 2^21108086656 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 21108086656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21423714840).

21108086656 is an abundant number, since it is smaller than the sum of its proper divisors (21739343024).

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

21108086656 is a wasteful number, since it uses less digits than its factorization.

21108086656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11751 (or 11739 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 43.

The spelling of 21108086656 in words is "twenty-one billion, one hundred eight million, eighty-six thousand, six hundred fifty-six".