198109 has 2 divisors, whose sum is σ = 198110. Its totient is φ = 198108.

The previous prime is 198097. The next prime is 198127. The reversal of 198109 is 901891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 142884 + 55225 = 378^2 + 235^2 .

It is an emirp because it is prime and its reverse (901891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 198109 - 2⁹ = 197597 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99054 + 99055.

It is an arithmetic number, because the mean of its divisors is an integer number (99055).

2¹⁹⁸¹⁰⁹ is an apocalyptic number.

It is an amenable number.

198109 is a deficient number, since it is larger than the sum of its proper divisors (1).

198109 is an equidigital number, since it uses as much as digits as its factorization.

198109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 198109 is about 445.0943720156. The cubic root of 198109 is about 58.2954602233.

It can be divided in two parts, 19 and 8109, that added together give a triangular number (8128 = T₁₂₇).

The spelling of 198109 in words is "one hundred ninety-eight thousand, one hundred nine".