216204209 has 16 divisors (see below), whose sum is σ = 249537792. Its totient is φ = 185727168.

The previous prime is 216204187. The next prime is 216204227. The reversal of 216204209 is 902402612.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216204209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216204239) by changing a digit.

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, 1292 + ... + 20834.

It is an arithmetic number, because the mean of its divisors is an integer number (15596112).

Almost surely, 2^216204209 is an apocalyptic number.

It is an amenable number.

216204209 is a deficient number, since it is larger than the sum of its proper divisors (33333583).

216204209 is a wasteful number, since it uses less digits than its factorization.

216204209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19616.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 216204209 is about 14703.8841467144. The cubic root of 216204209 is about 600.1890228518.

The spelling of 216204209 in words is "two hundred sixteen million, two hundred four thousand, two hundred nine".