21015232 has 56 divisors (see below), whose sum is σ = 48503840. Its totient is φ = 8847360.

The previous prime is 21015221. The next prime is 21015257. The reversal of 21015232 is 23251012.

It is a tau number, because it is divible by the number of its divisors (56).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26944 + ... + 27712.

It is an arithmetic number, because the mean of its divisors is an integer number (866140).

Almost surely, 2^21015232 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 21015232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24251920).

21015232 is an abundant number, since it is smaller than the sum of its proper divisors (27488608).

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

21015232 is an equidigital number, since it uses as much as digits as its factorization.

21015232 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 849 (or 839 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21015232 is about 4584.2373411507. The cubic root of 21015232 is about 275.9591061725.

Adding to 21015232 its reverse (23251012), we get a palindrome (44266244).

The spelling of 21015232 in words is "twenty-one million, fifteen thousand, two hundred thirty-two".