21331232 has 48 divisors (see below), whose sum is σ = 46230912. Its totient is φ = 9626880.

The previous prime is 21331217. The next prime is 21331267. The reversal of 21331232 is 23213312.

It is a self number, because there is not a number n which added to its sum of digits gives 21331232.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 19007 + ... + 20097.

It is an arithmetic number, because the mean of its divisors is an integer number (963144).

Almost surely, 2^21331232 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 21331232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23115456).

21331232 is an abundant number, since it is smaller than the sum of its proper divisors (24899680).

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

21331232 is a wasteful number, since it uses less digits than its factorization.

21331232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1161 (or 1153 counting only the distinct ones).

The product of its digits is 216, while the sum is 17.

The square root of 21331232 is about 4618.5746719091. The cubic root of 21331232 is about 277.3354032965.

Adding to 21331232 its reverse (23213312), we get a palindrome (44544544).

The spelling of 21331232 in words is "twenty-one million, three hundred thirty-one thousand, two hundred thirty-two".