21697998920 has 32 divisors (see below), whose sum is σ = 52575921720. Its totient is φ = 8011568640.

The previous prime is 21697998913. The next prime is 21697998929. The reversal of 21697998920 is 2989979612.

It can be written as a sum of positive squares in 4 ways, for example, as 16149834724 + 5548164196 = 127082^2 + 74486^2 .

It is not an unprimeable number, because it can be changed into a prime (21697998929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20862941 + ... + 20863980.

Almost surely, 2^21697998920 is an apocalyptic number.

21697998920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21697998920 is an abundant number, since it is smaller than the sum of its proper divisors (30877922800).

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

21697998920 is a wasteful number, since it uses less digits than its factorization.

21697998920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41726945 (or 41726941 counting only the distinct ones).

The product of its (nonzero) digits is 8817984, while the sum is 62.

The spelling of 21697998920 in words is "twenty-one billion, six hundred ninety-seven million, nine hundred ninety-eight thousand, nine hundred twenty".