21715488 has 36 divisors (see below), whose sum is σ = 61754238. Its totient is φ = 7238400.

The previous prime is 21715471. The next prime is 21715489. The reversal of 21715488 is 88451712.

21715488 is a `hidden beast` number, since 2 + 171 + 5 + 488 = 666.

It can be written as a sum of positive squares in only one way, i.e., 19607184 + 2108304 = 4428^2 + 1452^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21715489) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 37413 + ... + 37988.

Almost surely, 2^21715488 is an apocalyptic number.

It is an amenable number.

21715488 is an abundant number, since it is smaller than the sum of its proper divisors (40038750).

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

21715488 is a wasteful number, since it uses less digits than its factorization.

21715488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75417 (or 75406 counting only the distinct ones).

The product of its digits is 17920, while the sum is 36.

The square root of 21715488 is about 4659.9879828171. The cubic root of 21715488 is about 278.9907886117.

The spelling of 21715488 in words is "twenty-one million, seven hundred fifteen thousand, four hundred eighty-eight".