I think you're objective is to write your first coed, rather than to compress it to maximal density, so I'll limit my suggestions to:

• use strict
• declare variables using 'my'.
• use 3 or 4 spaces per indent level, they accumulate fast once you get into longer programs.
• At about this level, you might start breaking your program into routines ...

#!/usr/bin/perl
use warnings;

my ( $number )  = read_user_number();
my ( $factors ) = factor( $number );
output_number( $factors );
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Yes, I've added a complication ... though we generate an array of factors, I return and pass a reference to the array, rather than the list of values.