After I made sure that the number is prime, how can I do the process of collecting the initial setup before it?

Question

Java

Answer 1

FF9900 For example, we have the number 9 not prime, if I add the prime numbers before it 7 + 5 + 2 + 1 + 3 = 18..... and if the number is prime, for example 5, so 5 + 3 + 2 + 1 = 11

How do I do this addition process؟!