21909399020 has 48 divisors (see below), whose sum is σ = 46227736800. Its totient is φ = 8722306560.

The previous prime is 21909399007. The next prime is 21909399053. The reversal of 21909399020 is 2099390912.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8655155 + ... + 8657685.

It is an arithmetic number, because the mean of its divisors is an integer number (963077850).

Almost surely, 2^21909399020 is an apocalyptic number.

21909399020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21909399020 is an abundant number, since it is smaller than the sum of its proper divisors (24318337780).

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

21909399020 is a wasteful number, since it uses less digits than its factorization.

21909399020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4418 (or 4416 counting only the distinct ones).

The product of its (nonzero) digits is 78732, while the sum is 44.

The spelling of 21909399020 in words is "twenty-one billion, nine hundred nine million, three hundred ninety-nine thousand, twenty".