For a start, you can discard all the even numbers - those that end with 2, 4, 6, 8, 0 - except for the number 2 itself (which in this case, isn't in the list). This only leaves you with the number 11 - which happens to be a Prime number.
11 is the prime number.
11
It is 3
18
1111 = 1*1118 = 1*2*3221 = 1*3*724 = 1*3*23
A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite. The largest prime number between 18 and 24 is 23.
The gcf of 18 and 24 is 6 which is a composite number because it has more than two factors.
11
There is only one and it is 11
largest prime factor of 18 & 24 = 3factors of :18= 1, 3, 6, 9, 1824= 1, 2, 3,4, 6, 8, 12, 24,prime factors of 18 & 24 = 2, 3largest prime factor of 18 & 24 = 3
24
No even number greater than 2 is prime.