21806612 has 12 divisors (see below), whose sum is σ = 38205300. Its totient is φ = 10890816.

The previous prime is 21806593. The next prime is 21806621. The reversal of 21806612 is 21660812.

It can be written as a sum of positive squares in 2 ways, for example, as 15476356 + 6330256 = 3934^2 + 2516^2 .

It is a congruent number.

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, 1598 + ... + 6794.

It is an arithmetic number, because the mean of its divisors is an integer number (3183775).

Almost surely, 2^21806612 is an apocalyptic number.

It is an amenable number.

21806612 is a deficient number, since it is larger than the sum of its proper divisors (16398688).

21806612 is a wasteful number, since it uses less digits than its factorization.

21806612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6250 (or 6248 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21806612 is about 4669.7550256946. The cubic root of 21806612 is about 279.3804840380.

The spelling of 21806612 in words is "twenty-one million, eight hundred six thousand, six hundred twelve".