21813992 has 16 divisors (see below), whose sum is σ = 43307460. Its totient is φ = 10265344.

The previous prime is 21813973. The next prime is 21813997. The reversal of 21813992 is 29931812.

It can be written as a sum of positive squares in 2 ways, for example, as 21771556 + 42436 = 4666^2 + 206^2 .

It is not an unprimeable number, because it can be changed into a prime (21813997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80063 + ... + 80334.

Almost surely, 2^21813992 is an apocalyptic number.

It is an amenable number.

21813992 is a deficient number, since it is larger than the sum of its proper divisors (21493468).

21813992 is a wasteful number, since it uses less digits than its factorization.

21813992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160420 (or 160416 counting only the distinct ones).

The product of its digits is 7776, while the sum is 35.

The square root of 21813992 is about 4670.5451501939. The cubic root of 21813992 is about 279.4119973457.

The spelling of 21813992 in words is "twenty-one million, eight hundred thirteen thousand, nine hundred ninety-two".