Johnn,
For now, I'm watchin' the young coyotes turning around (can't hunt them, but will "chase" them!

)... She's not yet an accomplished woman like your daughter.
Dime,
No, there's no relation between these numbers. There should not have many stampings on the receiver too. Some only show the Crowned "H" and NITRO and the Rockwell hardness testing "dot" (also found on the bolt lugs) - all the stamping close to the recoil lug. You should have the S/N and Nitro Proofing on the left side of the barrel and HVA trademark with caliber on top.
There are many letters and numbers wich are found here and there on the stock, at strategic places, though. Some have numbers electro-penciled here and there, but it's not factory-made.
The 1640 proof stamping is as below;
The FN made receivers have different stampings wich includes a number, and they have more than on the 1640, though, like this one;
Are you 100% sure it's a 1640 and not a FN M/98?
A picture and / or the place the stamping is would help positive ID (but if it's a letter and or a number, then, it's a "view mark" or "fitter's mark"