What you have there is a large frame Mosler Screw Door Bank Safe. It could date as early as the 1880's to the early 1900's. The number you displayed is the "body" or production number. All door parts and body parts will be stamped with that number as all parts are hand fit and needed to be kept as a set. The true serial number would be stamped on a nickle plated dome (seems to be missing) that would be mounted on top of the center door pivot. That number could be looked up in the Mosler serial number ledger which would tell the manufacturing year.
The front "trap" door that is broken had the combination lock mounted to it. That is a cast piece which could be repaired if you have the other piece. The lock is a Yale/Mosler 5H friction fence lock that is unique to that safe design. The lock only locks the trap door and moves a bolt into the rotating inner assembly. Easily defeated by simply disassembling the door cover, if you know where to find hidden fasteners. The true security of the safe is in the interior time lock which is a Yale Triple L three movement piece. The door and body of the safe are made from laminated burglar proof steel which is drill and explosion proof. That along with the tight wedging screw door made it resistant to nitroglycerin attacks.
The external rust is not a problem. To restore the safe it will need to be blasted anyway. The big plus about it is the door threads and inner threads are in good condition. Those are the hardest parts to refresh if rusted. Most of the original graphics can be made out and could be replicated. That design is common among Mosler screw doors.
I previously documented the restoration on a similar safe although it was a double door model on keypicking.com. Unfortunately, that thread has lost all pictures since the tinypics.com hosting site was discontinued. If you need detailed information you can inquire through this thread or by a private message. Ya gotta love those old Mosler Screw Door Safes.
not sure I did correctly
with door unstuck and reassembled I wonder if the broken part that holds the lock might be available?
I thought I would add this photo it is open and I have the combination
here is a photo of the number stamped on the door that number seems to be on most of the parts the broken lock mount is what looks like cast iron The rest is pretty good except for the paint could you guess the age