Question: is 45 a prime no?
Answer: For 45, the answer is: No, 45 is not a prime number. The list of all positive divisors (i.e., the list of all integers that divide 45) is as follows: 1, 3, 5, 9, 15, 45. For 45 to be a prime number, it would have been required that 45 has only two divisors, i.e., itself and 1.