198959891 has 32 divisors (see below), whose sum is σ = 237178368. Its totient is φ = 165150720.

The previous prime is 198959869. The next prime is 198959903.

198959891 is nontrivially palindromic in base 10.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-198959891 is a prime.

It is a Duffinian number.

198959891 is a modest number, since divided by 59891 gives 1989 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 198959891.

It is not an unprimeable number, because it can be changed into a prime (198959801) 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 31 ways as a sum of consecutive naturals, for example, 774035 + ... + 774291.

It is an arithmetic number, because the mean of its divisors is an integer number (7411824).

Almost surely, 2^198959891 is an apocalyptic number.

198959891 is a deficient number, since it is larger than the sum of its proper divisors (38218477).

198959891 is a wasteful number, since it uses less digits than its factorization.

198959891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431.

The product of its digits is 2099520, while the sum is 59.

The square root of 198959891 is about 14105.3142822129. The cubic root of 198959891 is about 583.7880194475.

The spelling of 198959891 in words is "one hundred ninety-eight million, nine hundred fifty-nine thousand, eight hundred ninety-one".