21804416 has 16 divisors (see below), whose sum is σ = 43438740. Its totient is φ = 10902144.

The previous prime is 21804361. The next prime is 21804449. The reversal of 21804416 is 61440812.

It is a tau number, because it is divible by the number of its divisors (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85046 + ... + 85301.

Almost surely, 2^21804416 is an apocalyptic number.

It is an amenable number.

21804416 is a deficient number, since it is larger than the sum of its proper divisors (21634324).

21804416 is an equidigital number, since it uses as much as digits as its factorization.

21804416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170361 (or 170349 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21804416 is about 4669.5198896675. The cubic root of 21804416 is about 279.3711055349.

The spelling of 21804416 in words is "twenty-one million, eight hundred four thousand, four hundred sixteen".