21204305 has 8 divisors (see below), whose sum is σ = 25876800. Its totient is φ = 16675696.

The previous prime is 21204251. The next prime is 21204329. The reversal of 21204305 is 50340212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21204305 - 2⁶ = 21204241 is a prime.

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 7 ways as a sum of consecutive naturals, for example, 35645 + ... + 36234.

It is an arithmetic number, because the mean of its divisors is an integer number (3234600).

Almost surely, 2^21204305 is an apocalyptic number.

It is an amenable number.

21204305 is a deficient number, since it is larger than the sum of its proper divisors (4672495).

21204305 is an equidigital number, since it uses as much as digits as its factorization.

21204305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71943.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21204305 is about 4604.8132426842. The cubic root of 21204305 is about 276.7842333522.

Adding to 21204305 its reverse (50340212), we get a palindrome (71544517).

The spelling of 21204305 in words is "twenty-one million, two hundred four thousand, three hundred five".