Correct Answer: 463

Solution : Let's check each option –
First option: 145 is divisible by 1, 5, 29, 145. So, it is not a prime number.
Second option: 463 is divisible by only 1 and 463. The number of factors of 463 is two. So, it is a prime number.
Third option: 581 is divisible by 1, 7, 83, 581. So, it is not a prime number.
Fourth option: 651 is divisible by 1, 3, 7, 21, 31, 93, 217, 651. So, it is not a prime number.

Hence, the second option is correct.