21939984 has 180 divisors, whose sum is σ = 73217040. Its totient is φ = 6298560.

The previous prime is 21939977. The next prime is 21939997. The reversal of 21939984 is 48993912.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1154727 + ... + 1154745.

Almost surely, 2^21939984 is an apocalyptic number.

21939984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21939984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36608520).

21939984 is an abundant number, since it is smaller than the sum of its proper divisors (51277056).

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

21939984 is an equidigital number, since it uses as much as digits as its factorization.

21939984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62 (or 35 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 21939984 is about 4684.0136635155. The cubic root of 21939984 is about 279.9489022403.

The spelling of 21939984 in words is "twenty-one million, nine hundred thirty-nine thousand, nine hundred eighty-four".