21204205 has 8 divisors (see below), whose sum is σ = 27758304. Its totient is φ = 15421200.

The previous prime is 21204199. The next prime is 21204223. The reversal of 21204205 is 50240212.

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

It is not a de Polignac number, because 21204205 - 2⁷ = 21204077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 192711 + ... + 192820.

It is an arithmetic number, because the mean of its divisors is an integer number (3469788).

Almost surely, 2^21204205 is an apocalyptic number.

It is an amenable number.

21204205 is a deficient number, since it is larger than the sum of its proper divisors (6554099).

21204205 is a wasteful number, since it uses less digits than its factorization.

21204205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385547.

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 21204205 is about 4604.8023844678. The cubic root of 21204205 is about 276.7837982445.

Adding to 21204205 its reverse (50240212), we get a palindrome (71444417).

The spelling of 21204205 in words is "twenty-one million, two hundred four thousand, two hundred five".