Convert from gigaparsec to mile [Roman, ancient]

Unit Definition (gigaparsec)
The Gigaparsec is a non-metric unit of distance equal to one billion parsecs, 3.2616 billion light years, or 30.856 78 zettameters (30.856 78 x 1021 kilometers). The unit is used in astronomy.

Unit Definition (mile [Roman, ancient])
A non metric unit of length; a statute mile, used for distances over land, is defined as 5280 ft.; a nautical mile, used for distances along the surface of the oceans, is defined as one minute of arc measured along the equator, which equals 6080.27 fit or 1.1516 statute miles.