218450209 has 2 divisors, whose sum is σ = 218450210. Its totient is φ = 218450208.

The previous prime is 218450207. The next prime is 218450261. The reversal of 218450209 is 902054812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 208715809 + 9734400 = 14447^2 + 3120^2 .

It is a cyclic number.

It is not a de Polignac number, because 218450209 - 2¹ = 218450207 is a prime.

Together with 218450207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (218450207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109225104 + 109225105.

It is an arithmetic number, because the mean of its divisors is an integer number (109225105).

Almost surely, 2^218450209 is an apocalyptic number.

It is an amenable number.

218450209 is a deficient number, since it is larger than the sum of its proper divisors (1).

218450209 is an equidigital number, since it uses as much as digits as its factorization.

218450209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 218450209 is about 14780.0611974376. The cubic root of 218450209 is about 602.2601872688.

The spelling of 218450209 in words is "two hundred eighteen million, four hundred fifty thousand, two hundred nine".