21266568 has 48 divisors (see below), whose sum is σ = 58694220. Its totient is φ = 6953856.

The previous prime is 21266561. The next prime is 21266603. The reversal of 21266568 is 86566212.

It can be written as a sum of positive squares in 2 ways, for example, as 20629764 + 636804 = 4542^2 + 798^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21266561) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1030 + ... + 6602.

Almost surely, 2^21266568 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 21266568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29347110).

21266568 is an abundant number, since it is smaller than the sum of its proper divisors (37427652).

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

21266568 is a wasteful number, since it uses less digits than its factorization.

21266568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5638 (or 5631 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 21266568 is about 4611.5689304184. The cubic root of 21266568 is about 277.0548792811.

The spelling of 21266568 in words is "twenty-one million, two hundred sixty-six thousand, five hundred sixty-eight".