21696768 has 144 divisors (see below), whose sum is σ = 66552640. Its totient is φ = 6967296.

The previous prime is 21696757. The next prime is 21696793. The reversal of 21696768 is 86769612.

It is a tau number, because it is divible by the number of its divisors (144).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 297180 + ... + 297252.

Almost surely, 2^21696768 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 21696768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33276320).

21696768 is an abundant number, since it is smaller than the sum of its proper divisors (44855872).

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

21696768 is an equidigital number, since it uses as much as digits as its factorization.

21696768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141 (or 121 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 21696768 is about 4657.9789608799. The cubic root of 21696768 is about 278.9105968604.

The spelling of 21696768 in words is "twenty-one million, six hundred ninety-six thousand, seven hundred sixty-eight".