21866568 has 64 divisors (see below), whose sum is σ = 58368000. Its totient is φ = 6806592.

The previous prime is 21866567. The next prime is 21866597. The reversal of 21866568 is 86566812.

It is not an unprimeable number, because it can be changed into a prime (21866567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35721 + ... + 36327.

It is an arithmetic number, because the mean of its divisors is an integer number (912000).

Almost surely, 2^21866568 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 21866568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29184000).

21866568 is an abundant number, since it is smaller than the sum of its proper divisors (36501432).

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

21866568 is a wasteful number, since it uses less digits than its factorization.

21866568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714 (or 710 counting only the distinct ones).

The product of its digits is 138240, while the sum is 42.

The square root of 21866568 is about 4676.1702278681. The cubic root of 21866568 is about 279.6362964826.

The spelling of 21866568 in words is "twenty-one million, eight hundred sixty-six thousand, five hundred sixty-eight".