21806396 has 6 divisors (see below), whose sum is σ = 38161200. Its totient is φ = 10903196.

The previous prime is 21806381. The next prime is 21806413. The reversal of 21806396 is 69360812.

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, 2725796 + ... + 2725803.

It is an arithmetic number, because the mean of its divisors is an integer number (6360200).

Almost surely, 2^21806396 is an apocalyptic number.

It is an amenable number.

21806396 is a deficient number, since it is larger than the sum of its proper divisors (16354804).

21806396 is a wasteful number, since it uses less digits than its factorization.

21806396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5451603 (or 5451601 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21806396 is about 4669.7318980858. The cubic root of 21806396 is about 279.3795615902.

The spelling of 21806396 in words is "twenty-one million, eight hundred six thousand, three hundred ninety-six".