21156912 has 120 divisors (see below), whose sum is σ = 68606720. Its totient is φ = 5961600.

The previous prime is 21156907. The next prime is 21156913. The reversal of 21156912 is 21965112.

It is a super-2 number, since 2×21156912² = 895229850751488, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21156913) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 140037 + ... + 140187.

Almost surely, 2^21156912 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21156912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34303360).

21156912 is an abundant number, since it is smaller than the sum of its proper divisors (47449808).

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

21156912 is a wasteful number, since it uses less digits than its factorization.

21156912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311 (or 302 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 21156912 is about 4599.6643355793. The cubic root of 21156912 is about 276.5778692790.

The spelling of 21156912 in words is "twenty-one million, one hundred fifty-six thousand, nine hundred twelve".