21672288 has 72 divisors (see below), whose sum is σ = 67243176. Its totient is φ = 6566400.

The previous prime is 21672271. The next prime is 21672319. The reversal of 21672288 is 88227612.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (72).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 253 + ... + 6588.

It is an arithmetic number, because the mean of its divisors is an integer number (933933).

Almost surely, 2^21672288 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 21672288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33621588).

21672288 is an abundant number, since it is smaller than the sum of its proper divisors (45570888).

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

21672288 is a wasteful number, since it uses less digits than its factorization.

21672288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6868 (or 6857 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 21672288 is about 4655.3504701580. The cubic root of 21672288 is about 278.8056610948.

The spelling of 21672288 in words is "twenty-one million, six hundred seventy-two thousand, two hundred eighty-eight".