21712924 has 6 divisors (see below), whose sum is σ = 37997624. Its totient is φ = 10856460.

The previous prime is 21712907. The next prime is 21712931. The reversal of 21712924 is 42921712.

It is a junction number, because it is equal to n+sod(n) for n = 21712892 and 21712901.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2714112 + ... + 2714119.

Almost surely, 2^21712924 is an apocalyptic number.

It is an amenable number.

21712924 is a deficient number, since it is larger than the sum of its proper divisors (16284700).

21712924 is a wasteful number, since it uses less digits than its factorization.

21712924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5428235 (or 5428233 counting only the distinct ones).

The product of its digits is 2016, while the sum is 28.

The square root of 21712924 is about 4659.7128666904. The cubic root of 21712924 is about 278.9798078080.

The spelling of 21712924 in words is "twenty-one million, seven hundred twelve thousand, nine hundred twenty-four".