21279984 has 80 divisors (see below), whose sum is σ = 61496064. Its totient is φ = 6284800.

The previous prime is 21279959. The next prime is 21280001. The reversal of 21279984 is 48997212.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 21157 + ... + 22139.

Almost surely, 2^21279984 is an apocalyptic number.

21279984 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 21279984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30748032).

21279984 is an abundant number, since it is smaller than the sum of its proper divisors (40216080).

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

21279984 is a wasteful number, since it uses less digits than its factorization.

21279984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1046 (or 1040 counting only the distinct ones).

The product of its digits is 72576, while the sum is 42.

The square root of 21279984 is about 4613.0233036481. The cubic root of 21279984 is about 277.1131269952.

The spelling of 21279984 in words is "twenty-one million, two hundred seventy-nine thousand, nine hundred eighty-four".