21207686620 has 12 divisors (see below), whose sum is σ = 44536141944. Its totient is φ = 8483074640.

The previous prime is 21207686611. The next prime is 21207686623. The reversal of 21207686620 is 2668670212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21207686623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 530192146 + ... + 530192185.

It is an arithmetic number, because the mean of its divisors is an integer number (3711345162).

Almost surely, 2^21207686620 is an apocalyptic number.

21207686620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21207686620 is an abundant number, since it is smaller than the sum of its proper divisors (23328455324).

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

21207686620 is a wasteful number, since it uses less digits than its factorization.

21207686620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060384340 (or 1060384338 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 40.

The spelling of 21207686620 in words is "twenty-one billion, two hundred seven million, six hundred eighty-six thousand, six hundred twenty".