69 is a composite number because there is more than two factors of 69. 69 can be divided by 3 and 23 in addition to 1 and itself.
All numbers that only have one and itself as factors are prime. Therefore, to tell if a number is prime simply find it's factors. If it has more than two factors than it is not a prime number.
Prime numbers are numbers that are only divisible by 2 numbers (one and themselves), for example 13, 17 etc.
No. 69/3 = 23
Because it is divisible, by 3 for example.