There are 6 people on the island, each who can either be a knight or a knave. A knight tells the truth, whereas a knave tells the lie.
Person 1: The number of either knights or knaves is the multiple of another of the different kind.
Person 2: There are less knaves than knights here.
Person 3: There is an odd number of knaves.
Person 4: The number of knaves is not a perfect square.
Person 5: The product of two numbers of knights and knaves is a perfect cube.
Person 6: The product of two numbers of knights and knaves is a perfect square.
What is the least possible number of knaves there?