What is the least positive integer with exactly five distinct positive factors?
To have exactly five distinct positive factors, the integer must be of the form p^4, where p is a prime number. This is because the factors of p^4 are 1, p, p^2, p^3, and p^4, and there are no other factors. The smallest prime number is 2, so the smallest integer of the form p^4 is 2^4, which is 16. 