Because it work on google platform
Android and Windows Phone are two completely different software platforms. Android is an OS designed and maintained by a team at Google while Windows Phone is an OS designed and maintained by Microsoft. Each has their own unique look and design and has their own ecosystem of apps. When comparing popularity, Android holds an extremely higher percentage of the market share than Windows Phone does and also has a lot more third party apps and services available for it.
Regarding the compatibility for Google's platform, Android contains native support for just about all of Google's services whereas Windows Phone only contains a limited amount of native Google support. However, there are third party applications that can tie in with Google's services on either platform.
But that's enough of my random thoughts. The answer to your original question is X over 6 to the 14th power.