218207209 has 16 divisors (see below), whose sum is σ = 242288640. Its totient is φ = 194866560.

The previous prime is 218207203. The next prime is 218207221. The reversal of 218207209 is 902702812.

It is a cyclic number.

It is not a de Polignac number, because 218207209 - 2⁵ = 218207177 is a prime.

It is a super-2 number, since 2×218207209² = 95228772119139362, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (218207203) 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, 151557 + ... + 152989.

It is an arithmetic number, because the mean of its divisors is an integer number (15143040).

Almost surely, 2^218207209 is an apocalyptic number.

It is an amenable number.

218207209 is a deficient number, since it is larger than the sum of its proper divisors (24081431).

218207209 is a wasteful number, since it uses less digits than its factorization.

218207209 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 4032, while the sum is 31.

The square root of 218207209 is about 14771.8383757744. The cubic root of 218207209 is about 602.0367900239.

The spelling of 218207209 in words is "two hundred eighteen million, two hundred seven thousand, two hundred nine".