Determining Whether the Number $11111$ is Prime. Used Divisibility Tests. I am asked to determine whether the number $11111$ is prime. Upon using the divisibility tests for the numbers 1 to 11, I couldn't find anything that divides it, so I assumed that it is prime. However, it apparently isn't prime. So what is the procedure to determine whether $11111$ is prime?
Thank you for any help.

Here is a list for test of prime factor of less than $50$.
Test for divisibility by $41$. Subtract four times the last digit from the remaining leading truncated number. If the result is divisible by $41$, then so was the first number. Apply this rule over and over again as necessary. 
$$1111-4(1)=1107$$
$$110-4(7)=110-28=82$$
$$8-4(2)=0$$
The number is divisible by $41$.
