21579372 has 54 divisors (see below), whose sum is σ = 56950348. Its totient is φ = 7144848.

The previous prime is 21579367. The next prime is 21579373. The reversal of 21579372 is 27397512.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

21579372 is a `hidden beast` number, since 215 + 79 + 372 = 666.

It is a tau number, because it is divible by the number of its divisors (54).

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 (21579373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 144754 + ... + 144902.

Almost surely, 2^21579372 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 21579372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28475174).

21579372 is an abundant number, since it is smaller than the sum of its proper divisors (35370976).

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

21579372 is an equidigital number, since it uses as much as digits as its factorization.

21579372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317 (or 154 counting only the distinct ones).

The product of its digits is 26460, while the sum is 36.

The square root of 21579372 is about 4645.3602658997. The cubic root of 21579372 is about 278.4066474334.

The spelling of 21579372 in words is "twenty-one million, five hundred seventy-nine thousand, three hundred seventy-two".