21005320599564 has 96 divisors (see below), whose sum is σ = 60519531340800. Its totient is φ = 5648489554176.

The previous prime is 21005320599563. The next prime is 21005320599589. The reversal of 21005320599564 is 46599502350012.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is not an unprimeable number, because it can be changed into a prime (21005320599563) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 150028072 + ... + 150168015.

It is an arithmetic number, because the mean of its divisors is an integer number (630411784800).

Almost surely, 2^{21005320599564} is an apocalyptic number.

It is an amenable number.

21005320599564 is an abundant number, since it is smaller than the sum of its proper divisors (39514210741236).

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

21005320599564 is a wasteful number, since it uses less digits than its factorization.

21005320599564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300196132 (or 300196116 counting only the distinct ones).

The product of its (nonzero) digits is 2916000, while the sum is 51.

The spelling of 21005320599564 in words is "twenty-one trillion, five billion, three hundred twenty million, five hundred ninety-nine thousand, five hundred sixty-four".