36.2mp is the uncropped width times the uncropped height (in pixels, divided by one million), in other words: the number of megapixels in the source image. This number will never change, since cropping doesn't affect it.
Anyway, it is the maximum size of the embedded preview, but not necessarily the maximum Lr preview size, since the latter will be as-cropped, where-as the former will be uncropped (or as-cropped in mfr.software).
PS - if you export without resizing, exported jpeg file will be same dimensions (and hence same number of megapixels) as you see in Lightroom (e.g. 36.2mp, unless cropped..).
Thank-you for your help. One thing more. Is there a maximum size raw file that Lightroom can import? If you're importing a 75mb raw file, how can you tell that it has imported the whole file?
There is a limit to number of megapixels that Lr will support (I don't recall what it is, but it's in the specs..). That said, NO raw file will exceed it - the only files that will exceed it are those that have been stitched together like a pano (i.e. not raw).
PS - Lr will import whole file or none of it, so if it was imported, it's whole..
Thank-you again. You know your stuff.