21723772 has 24 divisors (see below), whose sum is σ = 44460416. Its totient is φ = 9093168.

The previous prime is 21723763. The next prime is 21723791. The reversal of 21723772 is 27732712.

It is a congruent number.

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, 7818 + ... + 10225.

Almost surely, 2^21723772 is an apocalyptic number.

It is an amenable number.

21723772 is an abundant number, since it is smaller than the sum of its proper divisors (22736644).

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

21723772 is a wasteful number, since it uses less digits than its factorization.

21723772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18097 (or 18095 counting only the distinct ones).

The product of its digits is 8232, while the sum is 31.

The square root of 21723772 is about 4660.8767415584. The cubic root of 21723772 is about 279.0262604659.

The spelling of 21723772 in words is "twenty-one million, seven hundred twenty-three thousand, seven hundred seventy-two".