Convert from arratel, artel [Arab] to megatonne

Unit Definition (arratel, artel [Arab])
The arratel is a versions of a traditional Arab unit of weight; see rotl. The spelling "arratel" is used in Portugal as an alternate name for the libra.

Unit Definition (megatonne)
The megatonne is a metric unit of mass or weight equal to one million metric tons (tonnes), one teragram (Tg), or about 2.2046 billion pounds.