gzip64

$ ls -l archive.tar*
-rw-r--r-- 1 matteo matteo 33375948800 gen 22 11:11 archive.tar
-rw-r--r-- 1 matteo matteo 10951536426 gen 20 23:44 archive.tar.gz

$ gzip -l archive.tar.gz
         compressed        uncompressed  ratio uncompressed_name
        10951536426          3311177728 -230.7% archive.tar

$ echo $((33375948800 & ((1<<32)-1)))
3311177728