RNY Q2

Since $2017$ is prime, so it has only $2$ factors.

*Proof : * $\displaystyle 44 < \sqrt { 2017 } < 45$ , so the largest prime below $\sqrt { 2017 }$ is $43$ .

So, there are a total of $14$ primes including $2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43$ .

But, $2017 \equiv 1 ( \mod 2 )$ .

$2017 \equiv 1 ( \mod 3 )$ .

$2017 \equiv 2 ( \mod 5 )$ .

Repeating these calculations, then we can get this.

2017 is not divisible by any prime numbers below $\sqrt { 2017 }$ .

So it is prime.

I've used this wiki of Brilliant.

Link : Prime numbers wiki of brilliant