21747612 has 12 divisors (see below), whose sum is σ = 50744456. Its totient is φ = 7249200.

The previous prime is 21747587. The next prime is 21747613. The reversal of 21747612 is 21674712.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21747612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21747613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 906139 + ... + 906162.

Almost surely, 2^21747612 is an apocalyptic number.

It is an amenable number.

21747612 is an abundant number, since it is smaller than the sum of its proper divisors (28996844).

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

21747612 is a wasteful number, since it uses less digits than its factorization.

21747612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1812308 (or 1812306 counting only the distinct ones).

The product of its digits is 4704, while the sum is 30.

The square root of 21747612 is about 4663.4334990434. The cubic root of 21747612 is about 279.1282923813.

Subtracting from 21747612 its reverse (21674712), we obtain a square (72900 = 270²).

The spelling of 21747612 in words is "twenty-one million, seven hundred forty-seven thousand, six hundred twelve".