21990912 has 80 divisors (see below), whose sum is σ = 59579520. Its totient is φ = 7206912.

The previous prime is 21990907. The next prime is 21990949. The reversal of 21990912 is 21909912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 158139 + ... + 158277.

It is an arithmetic number, because the mean of its divisors is an integer number (744744).

Almost surely, 2^21990912 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 21990912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29789760).

21990912 is an abundant number, since it is smaller than the sum of its proper divisors (37588608).

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

21990912 is a wasteful number, since it uses less digits than its factorization.

21990912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263 (or 247 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 21990912 is about 4689.4468756987. The cubic root of 21990912 is about 280.1653445190.

The spelling of 21990912 in words is "twenty-one million, nine hundred ninety thousand, nine hundred twelve".