Hello Amit,
You wouldn't get good texturing results when mesh is generated with the interpolation disabled. There are a lot of isolated mesh components in your model, so the number of texture atlas charts is extraordinary and their size is very small (therefore the atlas fill ratio is less than 1%).
I can suggest to use Enabled interpolation option. Also it may be reasonable to use smaller number of polygons in the model, unless you have a possibility to operate 50M polygons.