Problem 21

#!/usr/bin/perl
use strict;
use warnings;
use POSIX qw(floor);
 
my $sum = 1;
my %hash;
 
foreach my $n (1..10000){
    $sum = 1;
    foreach (2..floor($n**0.5)){
        if($n % $_ == 0){
                $sum += $_;
                $sum += $n/$_;
        }
    }
    $hash{$n} = $sum;
}
 
my $total = 0;
foreach my $key (keys %hash){
        my $value2 = 0;
        my $value1 = $hash{$key};
        if($value1<10000){
                $value2 = $hash{$value1};}
        if($key == $value2 && $value1 != $value2){
                $total += $key;}
}
 
print "$total\n";