A megahertz is one million (or 106) hertz.
See hertz, kilohertz (one thousand hertz), gigahertz[?] (109 hertz), terahertz[?] (1012 hertz), and petahertz[?] (1015 hertz).
... of proposing to Kitty. He first meets Stiva who encourages him in this plan, but, later that evening, Kitty rejects him in the expectation that Vronsky is about to propose ...