21493668 has 24 divisors (see below), whose sum is σ = 57316672. Its totient is φ = 6141024.

The previous prime is 21493657. The next prime is 21493691. The reversal of 21493668 is 86639412.

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, 127855 + ... + 128022.

Almost surely, 2^21493668 is an apocalyptic number.

21493668 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21493668 is an abundant number, since it is smaller than the sum of its proper divisors (35823004).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21493668 is a wasteful number, since it uses less digits than its factorization.

21493668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255891 (or 255889 counting only the distinct ones).

The product of its digits is 62208, while the sum is 39.

The square root of 21493668 is about 4636.1264003476. The cubic root of 21493668 is about 278.0375878648.

The spelling of 21493668 in words is "twenty-one million, four hundred ninety-three thousand, six hundred sixty-eight".