A slight twist which works for your two examples anyway.

sub dotless_to_ip {
    #use integer;
    my $dotless = shift;
    my $index   = 3;
    my @ip      = ();
    
    while ( @ip < 4 ) {
        my $temp = 256 ** $index--;
        push @ip, int($dotless / $temp) ;

        $dotless -= $ip[ -1 ] * $temp;
        
    }
    return join '.', @ip;
}
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I guess one could attack the problem using binary shifts (>>) and bitwise and's as well.