21156073220 has 12 divisors (see below), whose sum is σ = 44427753804. Its totient is φ = 8462429280.

The previous prime is 21156073219. The next prime is 21156073271. The reversal of 21156073220 is 2237065112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 15489295936 + 5666777284 = 124456^2 + 75278^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 528901811 + ... + 528901850.

It is an arithmetic number, because the mean of its divisors is an integer number (3702312817).

Almost surely, 2^21156073220 is an apocalyptic number.

21156073220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21156073220 is an abundant number, since it is smaller than the sum of its proper divisors (23271680584).

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

21156073220 is a wasteful number, since it uses less digits than its factorization.

21156073220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1057803670 (or 1057803668 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 29.

The spelling of 21156073220 in words is "twenty-one billion, one hundred fifty-six million, seventy-three thousand, two hundred twenty".