21568768 has 36 divisors (see below), whose sum is σ = 46372228. Its totient is φ = 9953280.

The previous prime is 21568763. The next prime is 21568787. The reversal of 21568768 is 86786512.

It can be written as a sum of positive squares in 2 ways, for example, as 12616704 + 8952064 = 3552^2 + 2992^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21568763) 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, 88 + ... + 6568.

Almost surely, 2^21568768 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 21568768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23186114).

21568768 is an abundant number, since it is smaller than the sum of its proper divisors (24803460).

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

21568768 is an equidigital number, since it uses as much as digits as its factorization.

21568768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6510 (or 6496 counting only the distinct ones).

The product of its digits is 161280, while the sum is 43.

The square root of 21568768 is about 4644.2187717634. The cubic root of 21568768 is about 278.3610373976.

The spelling of 21568768 in words is "twenty-one million, five hundred sixty-eight thousand, seven hundred sixty-eight".