198665209 has 2 divisors, whose sum is σ = 198665210. Its totient is φ = 198665208.

The previous prime is 198665183. The next prime is 198665219. The reversal of 198665209 is 902566891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 100100025 + 98565184 = 10005^2 + 9928^2 .

It is a cyclic number.

It is not a de Polignac number, because 198665209 - 2²³ = 190276601 is a prime.

It is not a weakly prime, because it can be changed into another prime (198665219) 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, 99332604 + 99332605.

It is an arithmetic number, because the mean of its divisors is an integer number (99332605).

Almost surely, 2^198665209 is an apocalyptic number.

It is an amenable number.

198665209 is a deficient number, since it is larger than the sum of its proper divisors (1).

198665209 is an equidigital number, since it uses as much as digits as its factorization.

198665209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 233280, while the sum is 46.

The square root of 198665209 is about 14094.8646321985. The cubic root of 198665209 is about 583.4996584399.

The spelling of 198665209 in words is "one hundred ninety-eight million, six hundred sixty-five thousand, two hundred nine".