A megahertz is one million (or 106) hertz. See hertz, kilohertz (one thousand hertz), gigahertz[?] (109 hertz), terahertz[?] (1012 hertz), and petahertz[?] (1015 hertz).
... families residing in the town. The population density is 326.2/km² (842.9/mi²). There are 928 housing units at an average density of 173.1/km² ...