21204433 has 4 divisors (see below), whose sum is σ = 21243060. Its totient is φ = 21165808.

The previous prime is 21204419. The next prime is 21204451. The reversal of 21204433 is 33440212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7006609 + 14197824 = 2647^2 + 3768^2 .

It is a cyclic number.

It is not a de Polignac number, because 21204433 - 2⁹ = 21203921 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21204433.

It is not an unprimeable number, because it can be changed into a prime (21204493) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18478 + ... + 19591.

It is an arithmetic number, because the mean of its divisors is an integer number (5310765).

Almost surely, 2^21204433 is an apocalyptic number.

It is an amenable number.

21204433 is a deficient number, since it is larger than the sum of its proper divisors (38627).

21204433 is an equidigital number, since it uses as much as digits as its factorization.

21204433 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38626.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21204433 is about 4604.8271411639. The cubic root of 21204433 is about 276.7847902880.

Adding to 21204433 its reverse (33440212), we get a palindrome (54644645).

The spelling of 21204433 in words is "twenty-one million, two hundred four thousand, four hundred thirty-three".