21537760640 has 64 divisors (see below), whose sum is σ = 56169519120. Its totient is φ = 7831910400.

The previous prime is 21537760627. The next prime is 21537760667. The reversal of 21537760640 is 4606773512.

It is a tau number, because it is divible by the number of its divisors (64).

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, 1522631 + ... + 1536710.

Almost surely, 2^21537760640 is an apocalyptic number.

21537760640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21537760640 is an abundant number, since it is smaller than the sum of its proper divisors (34631758480).

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

21537760640 is a wasteful number, since it uses less digits than its factorization.

21537760640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3059371 (or 3059359 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 41.

The spelling of 21537760640 in words is "twenty-one billion, five hundred thirty-seven million, seven hundred sixty thousand, six hundred forty".