How do get information of installed application with the corresponding .apk file name

[sibanee]

How do we find apk name corresponding to application installed on device. Assume that i have to all the root folders

Eg : If there is some xxxx.apk and application name is Email. Is there any way to know from device logs or device files that xxxx.apk is the apk name for Email application.?
Please help !!!

Thank You,