21609610520 has 32 divisors (see below), whose sum is σ = 51481720800. Its totient is φ = 8135382528.

The previous prime is 21609610513. The next prime is 21609610543. The reversal of 21609610520 is 2501690612.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15888740 + ... + 15890099.

It is an arithmetic number, because the mean of its divisors is an integer number (1608803775).

Almost surely, 2^21609610520 is an apocalyptic number.

21609610520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21609610520 is an abundant number, since it is smaller than the sum of its proper divisors (29872110280).

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

21609610520 is a wasteful number, since it uses less digits than its factorization.

21609610520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31778867 (or 31778863 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 32.

The spelling of 21609610520 in words is "twenty-one billion, six hundred nine million, six hundred ten thousand, five hundred twenty".