21581409984 has 56 divisors (see below), whose sum is σ = 57254089200. Its totient is φ = 7174493184.

The previous prime is 21581409947. The next prime is 21581410001. The reversal of 21581409984 is 48990418512.

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, 79059 + ... + 222290.

It is an arithmetic number, because the mean of its divisors is an integer number (1022394450).

Almost surely, 2^21581409984 is an apocalyptic number.

21581409984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21581409984 is an abundant number, since it is smaller than the sum of its proper divisors (35672679216).

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

21581409984 is a wasteful number, since it uses less digits than its factorization.

21581409984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301737 (or 301727 counting only the distinct ones).

The product of its (nonzero) digits is 829440, while the sum is 51.

The spelling of 21581409984 in words is "twenty-one billion, five hundred eighty-one million, four hundred nine thousand, nine hundred eighty-four".