21904992 has 96 divisors (see below), whose sum is σ = 64884960. Its totient is φ = 7278336.

The previous prime is 21904963. The next prime is 21905011. The reversal of 21904992 is 29940912.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69828 + ... + 70140.

It is an arithmetic number, because the mean of its divisors is an integer number (675885).

Almost surely, 2^21904992 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 21904992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32442480).

21904992 is an abundant number, since it is smaller than the sum of its proper divisors (42979968).

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

21904992 is an frugal number, since it uses more digits than its factorization.

21904992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344 (or 318 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 21904992 is about 4680.2769148844. The cubic root of 21904992 is about 279.7999932216.

The spelling of 21904992 in words is "twenty-one million, nine hundred four thousand, nine hundred ninety-two".