$geister = 999 ** 6;
printf "%.4g", $geister;

my @sieb=(0..$geister);    # sieb des erestothenes
for my $i (2..($#sieb/2)){
  next unless $sieb[$i];
  $sieb[$i*$_] = 0 for 2..int $#sieb/$i;
}

for my $prim (2..$geister) {
    if ($sieb[$prim]) {
       my $a;
       until ($geister % $prim){ $a++; $geister %= $prim; }
       print "$prim:$a " if $a;
    }
}