21406432 has 48 divisors (see below), whose sum is σ = 44174592. Its totient is φ = 10200960.

The previous prime is 21406397. The next prime is 21406457. The reversal of 21406432 is 23460412.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64507 + ... + 64837.

It is an arithmetic number, because the mean of its divisors is an integer number (920304).

Almost surely, 2^21406432 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 21406432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22087296).

21406432 is an abundant number, since it is smaller than the sum of its proper divisors (22768160).

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

21406432 is a wasteful number, since it uses less digits than its factorization.

21406432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431 (or 423 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 21406432 is about 4626.7085492821. The cubic root of 21406432 is about 277.6609222733.

Adding to 21406432 its reverse (23460412), we get a palindrome (44866844).

The spelling of 21406432 in words is "twenty-one million, four hundred six thousand, four hundred thirty-two".