198665 has 4 divisors (see below), whose sum is σ = 238404. Its totient is φ = 158928.

The previous prime is 198659. The next prime is 198673. The reversal of 198665 is 566891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566891 = 13 ⋅43607.

It can be written as a sum of positive squares in 2 ways, for example, as 139129 + 59536 = 373^2 + 244^2 .

It is a cyclic number.

It is not a de Polignac number, because 198665 - 2⁸ = 198409 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19862 + ... + 19871.

It is an arithmetic number, because the mean of its divisors is an integer number (59601).

2¹⁹⁸⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

198665 is a deficient number, since it is larger than the sum of its proper divisors (39739).

198665 is an equidigital number, since it uses as much as digits as its factorization.

198665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39738.

The product of its digits is 12960, while the sum is 35.

The square root of 198665 is about 445.7185210421. The cubic root of 198665 is about 58.3499453822.

The spelling of 198665 in words is "one hundred ninety-eight thousand, six hundred sixty-five".