198111 has 4 divisors (see below), whose sum is σ = 264152. Its totient is φ = 132072.

The previous prime is 198109. The next prime is 198127. The reversal of 198111 is 111891.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 198111 - 2¹ = 198109 is a prime.

It is an Ulam number.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (198811) 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 in 3 ways as a sum of consecutive naturals, for example, 33016 + ... + 33021.

It is an arithmetic number, because the mean of its divisors is an integer number (66038).

2¹⁹⁸¹¹¹ is an apocalyptic number.

198111 is a deficient number, since it is larger than the sum of its proper divisors (66041).

198111 is an equidigital number, since it uses as much as digits as its factorization.

198111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66040.

The product of its digits is 72, while the sum is 21.

The square root of 198111 is about 445.0966187245. The cubic root of 198111 is about 58.2956563957.

The spelling of 198111 in words is "one hundred ninety-eight thousand, one hundred eleven".