21311232 has 36 divisors (see below), whose sum is σ = 56721000. Its totient is φ = 7103488.

The previous prime is 21311219. The next prime is 21311237. The reversal of 21311232 is 23211312.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13107 + ... + 14642.

Almost surely, 2^21311232 is an apocalyptic number.

It is an amenable number.

21311232 is an abundant number, since it is smaller than the sum of its proper divisors (35409768).

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

21311232 is an equidigital number, since it uses as much as digits as its factorization.

21311232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27768 (or 27754 counting only the distinct ones).

The product of its digits is 72, while the sum is 15.

The square root of 21311232 is about 4616.4089940126. The cubic root of 21311232 is about 277.2487003424.

Adding to 21311232 its reverse (23211312), we get a palindrome (44522544).

The spelling of 21311232 in words is "twenty-one million, three hundred eleven thousand, two hundred thirty-two".