C# (largely inspired by Java) run on even more platforms, because there is compiler/runtimes for mobile platform. It’s also the second biggest "entreprise" language, which fix a lot of Java pain points.
Actually C# runs on less platforms than Java, because it doesn't run on embedded devices, M2M, bluray players, military deployments, mainframes, Xerox and Ricoh copiers, SIM and chip based credit cards, and plenty of others devices, like even having a mobile OS based on an Java dialect.