21930816 has 56 divisors (see below), whose sum is σ = 61447680. Its totient is φ = 6879232.

The previous prime is 21930809. The next prime is 21930851. The reversal of 21930816 is 61803912.

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, 96 + ... + 6623.

It is an arithmetic number, because the mean of its divisors is an integer number (1097280).

Almost surely, 2^21930816 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 21930816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30723840).

21930816 is an abundant number, since it is smaller than the sum of its proper divisors (39516864).

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

21930816 is a wasteful number, since it uses less digits than its factorization.

21930816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6751 (or 6741 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 21930816 is about 4683.0349133868. The cubic root of 21930816 is about 279.9099029849.

The spelling of 21930816 in words is "twenty-one million, nine hundred thirty thousand, eight hundred sixteen".