A megahertz is one million (or 106) hertz.
See hertz, kilohertz (one thousand hertz), gigahertz[?] (109 hertz), terahertz[?] (1012 hertz), and petahertz[?] (1015 hertz).
... and was a notary of Gothic kings in Italy. At the time of Justinian, he was a Christian and possibly bishop of Croton. In approximately 580, he wrote "De origine actibusque ...