21989992 has 16 divisors (see below), whose sum is σ = 43401600. Its totient is φ = 10416240.

The previous prime is 21989983. The next prime is 21989999. The reversal of 21989992 is 29998912.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21989999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72184 + ... + 72487.

It is an arithmetic number, because the mean of its divisors is an integer number (2712600).

Almost surely, 2^21989992 is an apocalyptic number.

It is an amenable number.

21989992 is a deficient number, since it is larger than the sum of its proper divisors (21411608).

21989992 is a wasteful number, since it uses less digits than its factorization.

21989992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144696 (or 144692 counting only the distinct ones).

The product of its digits is 209952, while the sum is 49.

The square root of 21989992 is about 4689.3487820805. The cubic root of 21989992 is about 280.1614375155.

The spelling of 21989992 in words is "twenty-one million, nine hundred eighty-nine thousand, nine hundred ninety-two".