21268564 has 12 divisors (see below), whose sum is σ = 39409524. Its totient is φ = 10008704.

The previous prime is 21268553. The next prime is 21268567. The reversal of 21268564 is 46586212.

It can be written as a sum of positive squares in 2 ways, for example, as 6980164 + 14288400 = 2642^2 + 3780^2 .

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21268567) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 156319 + ... + 156454.

It is an arithmetic number, because the mean of its divisors is an integer number (3284127).

Almost surely, 2^21268564 is an apocalyptic number.

It is an amenable number.

21268564 is a deficient number, since it is larger than the sum of its proper divisors (18140960).

21268564 is a wasteful number, since it uses less digits than its factorization.

21268564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312794 (or 312792 counting only the distinct ones).

The product of its digits is 23040, while the sum is 34.

The square root of 21268564 is about 4611.7853375889. The cubic root of 21268564 is about 277.0635467859.

The spelling of 21268564 in words is "twenty-one million, two hundred sixty-eight thousand, five hundred sixty-four".