21330205 has 16 divisors (see below), whose sum is σ = 27704880. Its totient is φ = 15671808.

The previous prime is 21330163. The next prime is 21330251. The reversal of 21330205 is 50203312.

It can be written as a sum of positive squares in 8 ways, for example, as 636804 + 20693401 = 798^2 + 4549^2 .

It is a cyclic number.

It is not a de Polignac number, because 21330205 - 2¹¹ = 21328157 is a prime.

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 15 ways as a sum of consecutive naturals, for example, 14169 + ... + 15601.

It is an arithmetic number, because the mean of its divisors is an integer number (1731555).

Almost surely, 2^21330205 is an apocalyptic number.

It is an amenable number.

21330205 is a deficient number, since it is larger than the sum of its proper divisors (6374675).

21330205 is a wasteful number, since it uses less digits than its factorization.

21330205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1680.

The product of its (nonzero) digits is 180, while the sum is 16.

The square root of 21330205 is about 4618.4634890838. The cubic root of 21330205 is about 277.3309524201.

Adding to 21330205 its reverse (50203312), we get a palindrome (71533517).

The spelling of 21330205 in words is "twenty-one million, three hundred thirty thousand, two hundred five".