21680568 has 128 divisors (see below), whose sum is σ = 74188800. Its totient is φ = 5712768.

The previous prime is 21680497. The next prime is 21680587. The reversal of 21680568 is 86508612.

It is a happy number.

21680568 is a `hidden beast` number, since 2 + 16 + 80 + 568 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19105 + ... + 20207.

It is an arithmetic number, because the mean of its divisors is an integer number (579600).

Almost surely, 2^21680568 is an apocalyptic number.

21680568 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21680568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37094400).

21680568 is an abundant number, since it is smaller than the sum of its proper divisors (52508232).

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

21680568 is a wasteful number, since it uses less digits than its factorization.

21680568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1138 (or 1128 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 21680568 is about 4656.2396845523. The cubic root of 21680568 is about 278.8411629139.

The spelling of 21680568 in words is "twenty-one million, six hundred eighty thousand, five hundred sixty-eight".