21680768 has 32 divisors (see below), whose sum is σ = 43623360. Its totient is φ = 10732288.

The previous prime is 21680741. The next prime is 21680783. The reversal of 21680768 is 86708612.

It is a tau number, because it is divible by the number of its divisors (32).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12905 + ... + 14487.

It is an arithmetic number, because the mean of its divisors is an integer number (1363230).

Almost surely, 2^21680768 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 21680768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21811680).

21680768 is an abundant number, since it is smaller than the sum of its proper divisors (21942592).

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

21680768 is a wasteful number, since it uses less digits than its factorization.

21680768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1704 (or 1692 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 21680768 is about 4656.2611610604. The cubic root of 21680768 is about 278.8420203340.

The spelling of 21680768 in words is "twenty-one million, six hundred eighty thousand, seven hundred sixty-eight".