21639472 has 20 divisors (see below), whose sum is σ = 42950376. Its totient is φ = 10555520.

The previous prime is 21639469. The next prime is 21639473. The reversal of 21639472 is 27493612.

It is not an unprimeable number, because it can be changed into a prime (21639473) 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, 15838 + ... + 17149.

Almost surely, 2^21639472 is an apocalyptic number.

It is an amenable number.

21639472 is a deficient number, since it is larger than the sum of its proper divisors (21310904).

21639472 is a wasteful number, since it uses less digits than its factorization.

21639472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33036 (or 33030 counting only the distinct ones).

The product of its digits is 18144, while the sum is 34.

The square root of 21639472 is about 4651.8245882664. The cubic root of 21639472 is about 278.6648682632.

The spelling of 21639472 in words is "twenty-one million, six hundred thirty-nine thousand, four hundred seventy-two".