21936818 has 16 divisors (see below), whose sum is σ = 34150680. Its totient is φ = 10555776.

The previous prime is 21936797. The next prime is 21936821. The reversal of 21936818 is 81863912.

It can be written as a sum of positive squares in 4 ways, for example, as 5396329 + 16540489 = 2323^2 + 4067^2 .

It is a Curzon 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, 35246 + ... + 35862.

Almost surely, 2^21936818 is an apocalyptic number.

21936818 is a deficient number, since it is larger than the sum of its proper divisors (12213862).

21936818 is a wasteful number, since it uses less digits than its factorization.

21936818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1261.

The product of its digits is 20736, while the sum is 38.

The square root of 21936818 is about 4683.6756932990. The cubic root of 21936818 is about 279.9354357938.

The spelling of 21936818 in words is "twenty-one million, nine hundred thirty-six thousand, eight hundred eighteen".