21645612 has 18 divisors (see below), whose sum is σ = 54715388. Its totient is φ = 7215192.

The previous prime is 21645551. The next prime is 21645619. The reversal of 21645612 is 21654612.

21645612 is a `hidden beast` number, since 2 + 1 + 6 + 45 + 612 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21645619) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 300598 + ... + 300669.

Almost surely, 2^21645612 is an apocalyptic number.

It is an amenable number.

21645612 is an abundant number, since it is smaller than the sum of its proper divisors (33069776).

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

21645612 is a wasteful number, since it uses less digits than its factorization.

21645612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601277 (or 601272 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21645612 is about 4652.4844975561. The cubic root of 21645612 is about 278.6912219636.

It can be divided in two parts, 2164 and 5612, that added together give a 5-th power (7776 = 6⁵).

The spelling of 21645612 in words is "twenty-one million, six hundred forty-five thousand, six hundred twelve".