21402432 has 84 divisors (see below), whose sum is σ = 62308740. Its totient is φ = 7022592.

The previous prime is 21402419. The next prime is 21402467. The reversal of 21402432 is 23420412.

It can be written as a sum of positive squares in 2 ways, for example, as 14930496 + 6471936 = 3864^2 + 2544^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41794 + ... + 42302.

Almost surely, 2^21402432 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 21402432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31154370).

21402432 is an abundant number, since it is smaller than the sum of its proper divisors (40906308).

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

21402432 is a wasteful number, since it uses less digits than its factorization.

21402432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600 (or 587 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21402432 is about 4626.2762563427. The cubic root of 21402432 is about 277.6436266481.

Adding to 21402432 its reverse (23420412), we get a palindrome (44822844).

The spelling of 21402432 in words is "twenty-one million, four hundred two thousand, four hundred thirty-two".