21243432 has 64 divisors (see below), whose sum is σ = 62668800. Its totient is φ = 5872320.

The previous prime is 21243403. The next prime is 21243437. The reversal of 21243432 is 23434212.

It is a Harshad number since it is a multiple of its sum of digits (21).

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

It is a junction number, because it is equal to n+sod(n) for n = 21243399 and 21243408.

It is not an unprimeable number, because it can be changed into a prime (21243437) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3169 + ... + 7247.

It is an arithmetic number, because the mean of its divisors is an integer number (979200).

Almost surely, 2^21243432 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 21243432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31334400).

21243432 is an abundant number, since it is smaller than the sum of its proper divisors (41425368).

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

21243432 is a wasteful number, since it uses less digits than its factorization.

21243432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4126 (or 4122 counting only the distinct ones).

The product of its digits is 1152, while the sum is 21.

The square root of 21243432 is about 4609.0597739669. The cubic root of 21243432 is about 276.9543730537.

Adding to 21243432 its reverse (23434212), we get a palindrome (44677644).

The spelling of 21243432 in words is "twenty-one million, two hundred forty-three thousand, four hundred thirty-two".