198391 has 2 divisors, whose sum is σ = 198392. Its totient is φ = 198390.

The previous prime is 198377. The next prime is 198397. The reversal of 198391 is 193891.

It is a strong prime.

It is an emirp because it is prime and its reverse (193891) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-198391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99195 + 99196.

It is an arithmetic number, because the mean of its divisors is an integer number (99196).

2¹⁹⁸³⁹¹ is an apocalyptic number.

198391 is a deficient number, since it is larger than the sum of its proper divisors (1).

198391 is an equidigital number, since it uses as much as digits as its factorization.

198391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 31.

The square root of 198391 is about 445.4110461136. The cubic root of 198391 is about 58.3231075046.

The spelling of 198391 in words is "one hundred ninety-eight thousand, three hundred ninety-one".