21968464 has 40 divisors (see below), whose sum is σ = 49649600. Its totient is φ = 9412704.

The previous prime is 21968459. The next prime is 21968477. The reversal of 21968464 is 46486912.

It is a super-2 number, since 2×21968464² = 965226821038592, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3487 + ... + 7489.

It is an arithmetic number, because the mean of its divisors is an integer number (1241240).

Almost surely, 2^21968464 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 21968464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24824800).

21968464 is an abundant number, since it is smaller than the sum of its proper divisors (27681136).

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

21968464 is an equidigital number, since it uses as much as digits as its factorization.

21968464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4032 (or 4012 counting only the distinct ones).

The product of its digits is 82944, while the sum is 40.

The square root of 21968464 is about 4687.0528053351. The cubic root of 21968464 is about 280.0699825073.

The spelling of 21968464 in words is "twenty-one million, nine hundred sixty-eight thousand, four hundred sixty-four".