21995816 has 16 divisors (see below), whose sum is σ = 41706900. Its totient is φ = 10873984.

The previous prime is 21995801. The next prime is 21995839. The reversal of 21995816 is 61859912.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20884900 + 1110916 = 4570^2 + 1054^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14735 + ... + 16158.

Almost surely, 2^21995816 is an apocalyptic number.

It is an amenable number.

21995816 is a deficient number, since it is larger than the sum of its proper divisors (19711084).

21995816 is a wasteful number, since it uses less digits than its factorization.

21995816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30988 (or 30984 counting only the distinct ones).

The product of its digits is 38880, while the sum is 41.

The square root of 21995816 is about 4689.9697227168. The cubic root of 21995816 is about 280.1861687082.

The spelling of 21995816 in words is "twenty-one million, nine hundred ninety-five thousand, eight hundred sixteen".