21993008 has 20 divisors (see below), whose sum is σ = 43127448. Its totient is φ = 10863360.

The previous prime is 21993007. The next prime is 21993067. The reversal of 21993008 is 80039912.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21993007) 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, 6953 + ... + 9608.

Almost surely, 2^21993008 is an apocalyptic number.

It is an amenable number.

21993008 is a deficient number, since it is larger than the sum of its proper divisors (21134440).

21993008 is a wasteful number, since it uses less digits than its factorization.

21993008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16652 (or 16646 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 21993008 is about 4689.6703508882. The cubic root of 21993008 is about 280.1742452854.

The spelling of 21993008 in words is "twenty-one million, nine hundred ninety-three thousand, eight".