21204992 has 52 divisors (see below), whose sum is σ = 44034816. Its totient is φ = 10199040.

The previous prime is 21204949. The next prime is 21205021. The reversal of 21204992 is 29940212.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126893 + ... + 127059.

Almost surely, 2^21204992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21204992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22017408).

21204992 is an abundant number, since it is smaller than the sum of its proper divisors (22829824).

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

21204992 is an equidigital number, since it uses as much as digits as its factorization.

21204992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222 (or 200 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21204992 is about 4604.8878379392. The cubic root of 21204992 is about 276.7872225048.

The spelling of 21204992 in words is "twenty-one million, two hundred four thousand, nine hundred ninety-two".