Question 902001
If {{{1}}} and {{{itself}}} are factors, then that leaves only one factor remaining to be found. 
If there is only one factor, it {{{must}}} be a {{{square}}} {{{root}}}. The largest perfect square with {{{four}}} digits is {{{9801}}}, but its square root is {{{not}}} a {{{prime}}} number; so there more than one additional factors. 
 The largest {{{prime}}} number less than {{{99}}} is {{{97}}} and {{{97^2=9409}}}. 
 
{{{9409}}} has factors {{{1}}}, {{{97}}}, and {{{9409}}}, and is the {{{largest}}} 4-digit number with three factors.