218001209 has 2 divisors, whose sum is σ = 218001210. Its totient is φ = 218001208.

The previous prime is 218001197. The next prime is 218001227. The reversal of 218001209 is 902100812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 190992400 + 27008809 = 13820^2 + 5197^2 .

It is a cyclic number.

It is not a de Polignac number, because 218001209 - 2⁸ = 218000953 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (218001229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109000604 + 109000605.

It is an arithmetic number, because the mean of its divisors is an integer number (109000605).

Almost surely, 2^218001209 is an apocalyptic number.

It is an amenable number.

218001209 is a deficient number, since it is larger than the sum of its proper divisors (1).

218001209 is an equidigital number, since it uses as much as digits as its factorization.

218001209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 218001209 is about 14764.8640020828. The cubic root of 218001209 is about 601.8472780658.

The spelling of 218001209 in words is "two hundred eighteen million, one thousand, two hundred nine".