21231432 has 48 divisors (see below), whose sum is σ = 57966480. Its totient is φ = 7020000.

The previous prime is 21231421. The next prime is 21231433. The reversal of 21231432 is 23413212.

21231432 is a `hidden beast` number, since 2 + 1 + 231 + 432 = 666.

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

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

It is not an unprimeable number, because it can be changed into a prime (21231433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8307 + ... + 10557.

It is an arithmetic number, because the mean of its divisors is an integer number (1207635).

It is a self-describing number.

Almost surely, 2^21231432 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 21231432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28983240).

21231432 is an abundant number, since it is smaller than the sum of its proper divisors (36735048).

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

21231432 is a wasteful number, since it uses less digits than its factorization.

21231432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2394 (or 2387 counting only the distinct ones).

The product of its digits is 288, while the sum is 18.

The square root of 21231432 is about 4607.7578061352. The cubic root of 21231432 is about 276.9022145252.

Adding to 21231432 its reverse (23413212), we get a palindrome (44644644).

The spelling of 21231432 in words is "twenty-one million, two hundred thirty-one thousand, four hundred thirty-two".