21356568 has 32 divisors (see below), whose sum is σ = 59324400. Its totient is φ = 7118784.

The previous prime is 21356567. The next prime is 21356579. The reversal of 21356568 is 86565312.

It is a super-2 number, since 2×21356568² = 912205993477248, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356563) 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, 49221 + ... + 49652.

Almost surely, 2^21356568 is an apocalyptic number.

It is an amenable number.

21356568 is an abundant number, since it is smaller than the sum of its proper divisors (37967832).

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

21356568 is a wasteful number, since it uses less digits than its factorization.

21356568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98888 (or 98878 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 21356568 is about 4621.3166954884. The cubic root of 21356568 is about 277.4451608216.

The spelling of 21356568 in words is "twenty-one million, three hundred fifty-six thousand, five hundred sixty-eight".