21312132 has 12 divisors (see below), whose sum is σ = 49728336. Its totient is φ = 7104040.

The previous prime is 21312121. The next prime is 21312149. The reversal of 21312132 is 23121312.

It is a tau number, because it is divible by the number of its divisors (12).

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 887994 + ... + 888017.

It is an arithmetic number, because the mean of its divisors is an integer number (4144028).

Almost surely, 2^21312132 is an apocalyptic number.

It is an amenable number.

21312132 is an abundant number, since it is smaller than the sum of its proper divisors (28416204).

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

21312132 is a wasteful number, since it uses less digits than its factorization.

21312132 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1776018 (or 1776016 counting only the distinct ones).

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

The square root of 21312132 is about 4616.5064713482. The cubic root of 21312132 is about 277.2526031407.

Adding to 21312132 its reverse (23121312), we get a palindrome (44433444).

The spelling of 21312132 in words is "twenty-one million, three hundred twelve thousand, one hundred thirty-two".