218308205809 has 2 divisors, whose sum is σ = 218308205810. Its totient is φ = 218308205808.

The previous prime is 218308205789. The next prime is 218308205813. The reversal of 218308205809 is 908502803812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 169473835584 + 48834370225 = 411672^2 + 220985^2 .

It is a cyclic number.

It is not a de Polignac number, because 218308205809 - 2⁷ = 218308205681 is a prime.

It is not a weakly prime, because it can be changed into another prime (218308205209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109154102904 + 109154102905.

It is an arithmetic number, because the mean of its divisors is an integer number (109154102905).

Almost surely, 2^218308205809 is an apocalyptic number.

It is an amenable number.

218308205809 is a deficient number, since it is larger than the sum of its proper divisors (1).

218308205809 is an equidigital number, since it uses as much as digits as its factorization.

218308205809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 276480, while the sum is 46.

The spelling of 218308205809 in words is "two hundred eighteen billion, three hundred eight million, two hundred five thousand, eight hundred nine".