198586991 has 16 divisors (see below), whose sum is σ = 211273920. Its totient is φ = 186278400.

The previous prime is 198586981. The next prime is 198587009. The reversal of 198586991 is 199685891.

198586991 = T₁₈₁₈ + T₁₈₁₉ + ... + T₁₉₃₀.

It is a cyclic number.

It is not a de Polignac number, because 198586991 - 2²² = 194392687 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 (198586901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 282941 + ... + 283641.

It is an arithmetic number, because the mean of its divisors is an integer number (13204620).

Almost surely, 2^198586991 is an apocalyptic number.

198586991 is a deficient number, since it is larger than the sum of its proper divisors (12686929).

198586991 is a wasteful number, since it uses less digits than its factorization.

198586991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 946.

The product of its digits is 1399680, while the sum is 56.

The square root of 198586991 is about 14092.0896605152. The cubic root of 198586991 is about 583.4230703488.

The spelling of 198586991 in words is "one hundred ninety-eight million, five hundred eighty-six thousand, nine hundred ninety-one".