21321984 has 36 divisors (see below), whose sum is σ = 56749616. Its totient is φ = 7107072.

The previous prime is 21321983. The next prime is 21321991. The reversal of 21321984 is 48912312.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21321983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13114 + ... + 14649.

Almost surely, 2^21321984 is an apocalyptic number.

21321984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21321984 is an abundant number, since it is smaller than the sum of its proper divisors (35427632).

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

21321984 is an equidigital number, since it uses as much as digits as its factorization.

21321984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27782 (or 27768 counting only the distinct ones).

The product of its digits is 3456, while the sum is 30.

The square root of 21321984 is about 4617.5733886967. The cubic root of 21321984 is about 277.2953185896.

The spelling of 21321984 in words is "twenty-one million, three hundred twenty-one thousand, nine hundred eighty-four".