198665191 has 4 divisors (see below), whose sum is σ = 207302832. Its totient is φ = 190027552.

The previous prime is 198665183. The next prime is 198665209. The reversal of 198665191 is 191566891.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 191566891 = 163 ⋅1175257.

It is a cyclic number.

It is not a de Polignac number, because 198665191 - 2³ = 198665183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (198665101) 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 in 3 ways as a sum of consecutive naturals, for example, 4318786 + ... + 4318831.

It is an arithmetic number, because the mean of its divisors is an integer number (51825708).

Almost surely, 2^198665191 is an apocalyptic number.

198665191 is a deficient number, since it is larger than the sum of its proper divisors (8637641).

198665191 is an equidigital number, since it uses as much as digits as its factorization.

198665191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8637640.

The product of its digits is 116640, while the sum is 46.

The square root of 198665191 is about 14094.8639936680. The cubic root of 198665191 is about 583.4996408173.

The spelling of 198665191 in words is "one hundred ninety-eight million, six hundred sixty-five thousand, one hundred ninety-one".