A megahertz is one million (or 106) hertz.
See hertz, kilohertz (one thousand hertz), gigahertz[?] (109 hertz), terahertz[?] (1012 hertz), and petahertz[?] (1015 hertz).
... Testament. His life is no doubt fitly characterized by the words under an old picture first referred to by Francescus Tolensis[?]: "In all things I sought quiet and ...