21945672 has 48 divisors (see below), whose sum is σ = 67928640. Its totient is φ = 6270048.

The previous prime is 21945667. The next prime is 21945673. The reversal of 21945672 is 27654912.

21945672 is a `hidden beast` number, since 2 + 1 + 94 + 567 + 2 = 666.

It is a super-2 number, since 2×21945672² = 963225039063168, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21945673) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 21268 + ... + 22275.

It is an arithmetic number, because the mean of its divisors is an integer number (1415180).

Almost surely, 2^21945672 is an apocalyptic number.

It is an amenable number.

21945672 is an abundant number, since it is smaller than the sum of its proper divisors (45982968).

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

21945672 is a wasteful number, since it uses less digits than its factorization.

21945672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43562 (or 43555 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 21945672 is about 4684.6207957528. The cubic root of 21945672 is about 279.9730926524.

The spelling of 21945672 in words is "twenty-one million, nine hundred forty-five thousand, six hundred seventy-two".