There are no greatest hole numbers nor least whole numbers so the question makes no sense.
greatest is 999 and least is 100
999
992
A single number cannot produce a product.
8*112
992
999
108.
999 , which is 9*111
-13, -15 and -17
If by "least number" you mean "smallest positive integer", then the answer is the product of the three smallest primes: 2x3x5 = 30
That would be 108... 9X12