21728568 has 32 divisors (see below), whose sum is σ = 54552960. Its totient is φ = 7212000.

The previous prime is 21728563. The next prime is 21728573. The reversal of 21728568 is 86582712.

It is an interprime number because it is at equal distance from previous prime (21728563) and next prime (21728573).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21728563) 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, 4221 + ... + 7827.

It is an arithmetic number, because the mean of its divisors is an integer number (1704780).

Almost surely, 2^21728568 is an apocalyptic number.

It is an amenable number.

21728568 is an abundant number, since it is smaller than the sum of its proper divisors (32824392).

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

21728568 is a wasteful number, since it uses less digits than its factorization.

21728568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3867 (or 3863 counting only the distinct ones).

The product of its digits is 53760, while the sum is 39.

The square root of 21728568 is about 4661.3912086415. The cubic root of 21728568 is about 279.0467926810.

The spelling of 21728568 in words is "twenty-one million, seven hundred twenty-eight thousand, five hundred sixty-eight".