21618423860 has 36 divisors (see below), whose sum is σ = 49901045124. Its totient is φ = 7861244160.

The previous prime is 21618423823. The next prime is 21618423913. The reversal of 21618423860 is 6832481612.

It can be written as a sum of positive squares in 2 ways, for example, as 4690332196 + 16928091664 = 68486^2 + 130108^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4464197 + ... + 4469036.

Almost surely, 2^21618423860 is an apocalyptic number.

21618423860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21618423860 is an abundant number, since it is smaller than the sum of its proper divisors (28282621264).

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

21618423860 is a wasteful number, since it uses less digits than its factorization.

21618423860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8933264 (or 8933251 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 41.

The spelling of 21618423860 in words is "twenty-one billion, six hundred eighteen million, four hundred twenty-three thousand, eight hundred sixty".