21518912 has 28 divisors (see below), whose sum is σ = 43226736. Its totient is φ = 10627200.

The previous prime is 21518881. The next prime is 21518933. The reversal of 21518912 is 21981512.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3287 + ... + 7337.

It is an arithmetic number, because the mean of its divisors is an integer number (1543812).

Almost surely, 2^21518912 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 21518912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21613368).

21518912 is an abundant number, since it is smaller than the sum of its proper divisors (21707824).

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

21518912 is an equidigital number, since it uses as much as digits as its factorization.

21518912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4146 (or 4136 counting only the distinct ones).

The product of its digits is 1440, while the sum is 29.

The square root of 21518912 is about 4638.8481328882. The cubic root of 21518912 is about 278.1463956439.

The spelling of 21518912 in words is "twenty-one million, five hundred eighteen thousand, nine hundred twelve".