21745672 has 32 divisors (see below), whose sum is σ = 45823680. Its totient is φ = 9599040.

The previous prime is 21745651. The next prime is 21745687. The reversal of 21745672 is 27654712.

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

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, 2154 + ... + 6937.

It is an arithmetic number, because the mean of its divisors is an integer number (1431990).

Almost surely, 2^21745672 is an apocalyptic number.

It is an amenable number.

21745672 is an abundant number, since it is smaller than the sum of its proper divisors (24078008).

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

21745672 is a wasteful number, since it uses less digits than its factorization.

21745672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9133 (or 9129 counting only the distinct ones).

The product of its digits is 23520, while the sum is 34.

The square root of 21745672 is about 4663.2254931539. The cubic root of 21745672 is about 279.1199922364.

The spelling of 21745672 in words is "twenty-one million, seven hundred forty-five thousand, six hundred seventy-two".