21173764640 has 48 divisors (see below), whose sum is σ = 57169167552. Its totient is φ = 7259576064.

The previous prime is 21173764613. The next prime is 21173764663. The reversal of 21173764640 is 4646737112.

It is a super-2 number, since 2×21173764640² (a number of 21 digits) contains 22 as substring.

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, 9451454 + ... + 9453693.

It is an arithmetic number, because the mean of its divisors is an integer number (1191024324).

Almost surely, 2^21173764640 is an apocalyptic number.

21173764640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21173764640 is an abundant number, since it is smaller than the sum of its proper divisors (35995402912).

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

21173764640 is a wasteful number, since it uses less digits than its factorization.

21173764640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18905169 (or 18905161 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 41.

The spelling of 21173764640 in words is "twenty-one billion, one hundred seventy-three million, seven hundred sixty-four thousand, six hundred forty".