21915712 has 112 divisors (see below), whose sum is σ = 55302912. Its totient is φ = 8386560.

The previous prime is 21915701. The next prime is 21915739. The reversal of 21915712 is 21751912.

It is a tau number, because it is divible by the number of its divisors (112).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 308637 + ... + 308707.

It is an arithmetic number, because the mean of its divisors is an integer number (493776).

Almost surely, 2^21915712 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 21915712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27651456).

21915712 is an abundant number, since it is smaller than the sum of its proper divisors (33387200).

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

21915712 is a wasteful number, since it uses less digits than its factorization.

21915712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156 (or 146 counting only the distinct ones).

The product of its digits is 1260, while the sum is 28.

The square root of 21915712 is about 4681.4220061857. The cubic root of 21915712 is about 279.8456291930.

It can be divided in two parts, 219 and 15712, that added together give a triangular number (15931 = T₁₇₈).

The spelling of 21915712 in words is "twenty-one million, nine hundred fifteen thousand, seven hundred twelve".