198936809 has 2 divisors, whose sum is σ = 198936810. Its totient is φ = 198936808.

The previous prime is 198936769. The next prime is 198936811. The reversal of 198936809 is 908639891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114811225 + 84125584 = 10715^2 + 9172^2 .

It is a cyclic number.

It is not a de Polignac number, because 198936809 - 2⁸ = 198936553 is a prime.

Together with 198936811, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (198936209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99468404 + 99468405.

It is an arithmetic number, because the mean of its divisors is an integer number (99468405).

Almost surely, 2^198936809 is an apocalyptic number.

It is an amenable number.

198936809 is a deficient number, since it is larger than the sum of its proper divisors (1).

198936809 is an equidigital number, since it uses as much as digits as its factorization.

198936809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 839808, while the sum is 53.

The square root of 198936809 is about 14104.4960562226. The cubic root of 198936809 is about 583.7654428432.

The spelling of 198936809 in words is "one hundred ninety-eight million, nine hundred thirty-six thousand, eight hundred nine".