218209 has 4 divisors (see below), whose sum is σ = 225280. Its totient is φ = 211140.

The previous prime is 218191. The next prime is 218213. The reversal of 218209 is 902812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 218209 - 2⁷ = 218081 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 218209.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218249) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3489 + ... + 3550.

It is an arithmetic number, because the mean of its divisors is an integer number (56320).

2²¹⁸²⁰⁹ is an apocalyptic number.

It is an amenable number.

218209 is a deficient number, since it is larger than the sum of its proper divisors (7071).

218209 is an equidigital number, since it uses as much as digits as its factorization.

218209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7070.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 218209 is about 467.1284619888. The cubic root of 218209 is about 60.2038437151.

The spelling of 218209 in words is "two hundred eighteen thousand, two hundred nine".