23 is the answer
Seven of them.
There are six prime numbers that are less than 15: 2 3 5 7 11 and 136 of them.
There are 15 composite numbers greater than 50 but less than 70
One of them.
The prime numbers that are greater than 80 and less than 100 are 83, 89, and 97.
24 of them.
There are 24. 3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97
23 29.
There are infinitely many prime numbers which are greater than 30.
Two. 23 and 29.
Three: 41 43 47.
83 89 97.
Two: 23 29
41 43 47.
Two: 53 and 59
Two: 23 29