198791 has 4 divisors (see below), whose sum is σ = 199800. Its totient is φ = 197784.

The previous prime is 198769. The next prime is 198811. The reversal of 198791 is 197891.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 198791 - 2¹⁰ = 197767 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 (198701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101 + ... + 638.

It is an arithmetic number, because the mean of its divisors is an integer number (49950).

2¹⁹⁸⁷⁹¹ is an apocalyptic number.

198791 is a deficient number, since it is larger than the sum of its proper divisors (1009).

198791 is an equidigital number, since it uses as much as digits as its factorization.

198791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1008.

The product of its digits is 4536, while the sum is 35.

The square root of 198791 is about 445.8598434486. The cubic root of 198791 is about 58.3622786054.

Subtracting from 198791 its reverse (197891), we obtain a square (900 = 30²).

It can be divided in two parts, 198 and 791, that added together give a palindrome (989).

The spelling of 198791 in words is "one hundred ninety-eight thousand, seven hundred ninety-one".