21968736 has 24 divisors (see below), whose sum is σ = 57668184. Its totient is φ = 7322880.

The previous prime is 21968717. The next prime is 21968741. The reversal of 21968736 is 63786912.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×21968736² = 965250722875392, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114325 + ... + 114516.

It is an arithmetic number, because the mean of its divisors is an integer number (2402841).

Almost surely, 2^21968736 is an apocalyptic number.

It is an amenable number.

21968736 is an abundant number, since it is smaller than the sum of its proper divisors (35699448).

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

21968736 is a wasteful number, since it uses less digits than its factorization.

21968736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228854 (or 228846 counting only the distinct ones).

The product of its digits is 108864, while the sum is 42.

The square root of 21968736 is about 4687.0818213468. The cubic root of 21968736 is about 280.0711383872.

The spelling of 21968736 in words is "twenty-one million, nine hundred sixty-eight thousand, seven hundred thirty-six".