21432 has 32 divisors (see below), whose sum is σ = 57600. Its totient is φ = 6624.

The previous prime is 21419. The next prime is 21433. The reversal of 21432 is 23412.

21432 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (12).

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

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21432.

It is not an unprimeable number, because it can be changed into a prime (21433) by changing a digit.

21432 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 433 + ... + 479.

It is an arithmetic number, because the mean of its divisors is an integer number (1800).

2²¹⁴³² 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 21432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28800).

21432 is an abundant number, since it is smaller than the sum of its proper divisors (36168).

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

21432 is a wasteful number, since it uses less digits than its factorization.

21432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75 (or 71 counting only the distinct ones).

The product of its digits is 48, while the sum is 12.

The square root of 21432 is about 146.3967212748. The cubic root of 21432 is about 27.7771425040. Note that the first 3 decimals are identical.

Adding to 21432 its reverse (23412), we get a palindrome (44844).

It can be divided in two parts, 2143 and 2, that added together give a triangular number (2145 = T₆₅).

The spelling of 21432 in words is "twenty-one thousand, four hundred thirty-two".