21645562104 has 48 divisors (see below), whose sum is σ = 60207820920. Its totient is φ = 7020181440.

The previous prime is 21645562093. The next prime is 21645562139. The reversal of 21645562104 is 40126554612.

21645562104 is a `hidden beast` number, since 2 + 1 + 645 + 5 + 6 + 2 + 1 + 0 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4059942 + ... + 4065269.

Almost surely, 2^21645562104 is an apocalyptic number.

21645562104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21645562104 is an abundant number, since it is smaller than the sum of its proper divisors (38562258816).

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

21645562104 is a wasteful number, since it uses less digits than its factorization.

21645562104 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8125260 (or 8125253 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The spelling of 21645562104 in words is "twenty-one billion, six hundred forty-five million, five hundred sixty-two thousand, one hundred four".