21405612 has 12 divisors (see below), whose sum is σ = 49946456. Its totient is φ = 7135200.

The previous prime is 21405611. The next prime is 21405619. The reversal of 21405612 is 21650412.

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

It is not an unprimeable number, because it can be changed into a prime (21405611) 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, 891889 + ... + 891912.

Almost surely, 2^21405612 is an apocalyptic number.

It is an amenable number.

21405612 is an abundant number, since it is smaller than the sum of its proper divisors (28540844).

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

21405612 is a wasteful number, since it uses less digits than its factorization.

21405612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1783808 (or 1783806 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21405612 is about 4626.6199325209. The cubic root of 21405612 is about 277.6573768457.

The spelling of 21405612 in words is "twenty-one million, four hundred five thousand, six hundred twelve".