21585612 has 12 divisors (see below), whose sum is σ = 50366456. Its totient is φ = 7195200.

The previous prime is 21585611. The next prime is 21585617. The reversal of 21585612 is 21658512.

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 21585612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21585611) 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 3 ways as a sum of consecutive naturals, for example, 899389 + ... + 899412.

Almost surely, 2^21585612 is an apocalyptic number.

It is an amenable number.

21585612 is an abundant number, since it is smaller than the sum of its proper divisors (28780844).

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

21585612 is a wasteful number, since it uses less digits than its factorization.

21585612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1798808 (or 1798806 counting only the distinct ones).

The product of its digits is 4800, while the sum is 30.

The square root of 21585612 is about 4646.0318552502. The cubic root of 21585612 is about 278.4334800038.

Subtracting 21585612 from its reverse (21658512), we obtain a square (72900 = 270²).

The spelling of 21585612 in words is "twenty-one million, five hundred eighty-five thousand, six hundred twelve".