21043332 has 72 divisors (see below), whose sum is σ = 55724760. Its totient is φ = 6689280.

The previous prime is 21043313. The next prime is 21043339. The reversal of 21043332 is 23334012.

It can be written as a sum of positive squares in 4 ways, for example, as 30276 + 21013056 = 174^2 + 4584^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21043339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78094 + ... + 78362.

It is an arithmetic number, because the mean of its divisors is an integer number (773955).

Almost surely, 2^21043332 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 21043332, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27862380).

21043332 is an abundant number, since it is smaller than the sum of its proper divisors (34681428).

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

21043332 is a wasteful number, since it uses less digits than its factorization.

21043332 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373 (or 368 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 18.

The square root of 21043332 is about 4587.3011673532. The cubic root of 21043332 is about 276.0820487002.

Adding to 21043332 its reverse (23334012), we get a palindrome (44377344).

The spelling of 21043332 in words is "twenty-one million, forty-three thousand, three hundred thirty-two".