Unlike other makes who did include factory information in the VIN, the 1952 Cadillac did not. Unit numbers began with 00000 for all series

most likely the 46787 represents the build number or where in the production cycle your car was built. Keep in mind that number probably started at 1001 and for each model/style built the number was incremented up. I once had a Station Wagon (Pontiac) that was serial num. 1041 and since they started at 1001, that car was the 40th car built. I think Cadillac operated in much the same manner?