Hi Shubham,
The points you have above are in the Web Mercator spatial reference. If you want to convert this to decimal degrees it is likely you want to be using the WGS84 spatial reference. Converting geometries from one spatial reference to another is easy and can be achieved generally in one line of code. You need to be looking at the project method on the GeometryEngine class.
In the code below I've recreated one of your points and converted it to WGS84 as an example.
// original point in web mercator
Point webMercPoint = new Point(8615608,2661384,SpatialReferences.getWebMercator());
// convert to point to WGS 84
Point wgs84Point = (Point) GeometryEngine.project(webMercPoint, SpatialReferences.getWgs84());
// show wgs 84 coordinates
System.out.println("wgs84 x:" + wgs84Point.getX() + " y:" + wgs84Point.getY());
Debug output is this:
wgs84 x:77.39532348382421 y:23.242604224773828
Does that help?