21204432 has 30 divisors (see below), whose sum is σ = 59343362. Its totient is φ = 7068096.

The previous prime is 21204419. The next prime is 21204451. The reversal of 21204432 is 23440212.

It can be written as a sum of positive squares in only one way, i.e., 14107536 + 7096896 = 3756^2 + 2664^2 .

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 pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 73483 + ... + 73770.

Almost surely, 2^21204432 is an apocalyptic number.

It is an amenable number.

21204432 is an abundant number, since it is smaller than the sum of its proper divisors (38138930).

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

21204432 is a wasteful number, since it uses less digits than its factorization.

21204432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147267 (or 147258 counting only the distinct ones).

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

The square root of 21204432 is about 4604.8270325822. The cubic root of 21204432 is about 276.7847859369.

Adding to 21204432 its reverse (23440212), we get a palindrome (44644644).

The spelling of 21204432 in words is "twenty-one million, two hundred four thousand, four hundred thirty-two".