If restricted to integers, the answer is 1 - for any prime number.
That would depend entirely on the given number.
3, 10
15,4 10,60
4 and 9 12 and 18
4 and 9 12 and 17
9 and 12 12 and 18
18 and 36 12 and 36
1 and 36 or 2 and 36 are two possible pairs.
(3, 36) and (4, 9)
15 and 21 21 and 35
2 and 5 5 and 10
The product of all pairs of prime numbers is always the least common multiple of the two prime numbers.