21806684 has 24 divisors (see below), whose sum is σ = 39240768. Its totient is φ = 10598400.

The previous prime is 21806663. The next prime is 21806723. The reversal of 21806684 is 48660812.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35984 + ... + 36584.

It is an arithmetic number, because the mean of its divisors is an integer number (1635032).

Almost surely, 2^21806684 is an apocalyptic number.

It is an amenable number.

21806684 is a deficient number, since it is larger than the sum of its proper divisors (17434084).

21806684 is a wasteful number, since it uses less digits than its factorization.

21806684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 845 (or 843 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 21806684 is about 4669.7627348721. The cubic root of 21806684 is about 279.3807915193.

The spelling of 21806684 in words is "twenty-one million, eight hundred six thousand, six hundred eighty-four".