21663672 has 16 divisors (see below), whose sum is σ = 54159240. Its totient is φ = 7221216.

The previous prime is 21663659. The next prime is 21663683. The reversal of 21663672 is 27636612.

It is a congruent number.

It is an unprimeable number.

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, 451303 + ... + 451350.

Almost surely, 2^21663672 is an apocalyptic number.

It is an amenable number.

21663672 is an abundant number, since it is smaller than the sum of its proper divisors (32495568).

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

21663672 is a wasteful number, since it uses less digits than its factorization.

21663672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 902662 (or 902658 counting only the distinct ones).

The product of its digits is 18144, while the sum is 33.

The square root of 21663672 is about 4654.4249913389. The cubic root of 21663672 is about 278.7687090206.

The spelling of 21663672 in words is "twenty-one million, six hundred sixty-three thousand, six hundred seventy-two".