21221568 has 56 divisors (see below), whose sum is σ = 62392560. Its totient is φ = 7073280.

The previous prime is 21221561. The next prime is 21221569. The reversal of 21221568 is 86512212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21221561) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4413 + ... + 7868.

Almost surely, 2^21221568 is an apocalyptic number.

It is an amenable number.

21221568 is an abundant number, since it is smaller than the sum of its proper divisors (41170992).

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

21221568 is a wasteful number, since it uses less digits than its factorization.

21221568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12302 (or 12286 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 21221568 is about 4606.6873130266. The cubic root of 21221568 is about 276.8593254956.

The spelling of 21221568 in words is "twenty-one million, two hundred twenty-one thousand, five hundred sixty-eight".