21308912 has 20 divisors (see below), whose sum is σ = 41987640. Its totient is φ = 10473408.

The previous prime is 21308897. The next prime is 21308921. The reversal of 21308912 is 21980312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10343 + ... + 12230.

It is an arithmetic number, because the mean of its divisors is an integer number (2099382).

Almost surely, 2^21308912 is an apocalyptic number.

It is an amenable number.

21308912 is a deficient number, since it is larger than the sum of its proper divisors (20678728).

21308912 is a wasteful number, since it uses less digits than its factorization.

21308912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22640 (or 22634 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21308912 is about 4616.1577096109. The cubic root of 21308912 is about 277.2386392891.

The spelling of 21308912 in words is "twenty-one million, three hundred eight thousand, nine hundred twelve".