21156612 has 24 divisors (see below), whose sum is σ = 49847616. Its totient is φ = 6983328.

The previous prime is 21156607. The next prime is 21156613. The reversal of 21156612 is 21665112.

It is not an unprimeable number, because it can be changed into a prime (21156613) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7323 + ... + 9794.

It is an arithmetic number, because the mean of its divisors is an integer number (2076984).

Almost surely, 2^21156612 is an apocalyptic number.

It is an amenable number.

21156612 is an abundant number, since it is smaller than the sum of its proper divisors (28691004).

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

21156612 is a wasteful number, since it uses less digits than its factorization.

21156612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17227 (or 17225 counting only the distinct ones).

The product of its digits is 720, while the sum is 24.

The square root of 21156612 is about 4599.6317243884. The cubic root of 21156612 is about 276.5765620032.

The spelling of 21156612 in words is "twenty-one million, one hundred fifty-six thousand, six hundred twelve".