You rarely see a 24-25" door on anything but a bathroom. The old BOCA code required 30" doors for everything but bathrooms (and a 36" front door). Interestingly, the new international code is more lenient, but I’ve had building inspectors insist on 30" doors for a new bathroom. I think 25" is uncomfortably narrow for a major room, so I’d seriously consider widening that door permanently if it’s feasible. That said, if you google “apartment size stove” you’ll find lots of slide in 20" wide stoves and oven combo both gas and electric.
That’s what I thought! In our town, kitchen doors have to be at least 30". OP would probably need to find something to fill the 5-10" gap created by the smaller range.
I originally had an opening just barely big enough to move a fridge in, sans doors. Old house. Even after a bit of widening, the 36" corner cabinet had to be lifted through the window (luckily, 40" wide.)
3" filler panels on either side of a 24" range would probably do it. They can match the existing cabinet style, more or less. But realize, this seems to leave a gap on the counters, no?
Here is something to keep in mind if you decide to replace the 30" oven with an “apartment size” one. If the renters cook or bake, they might be unhappy with the downsized range.
Yes, the tenant’s cooking habits should be considered, although we mostly have been getting students who rent the place for one year or so and move on, and don’t do too much cooking. But it might be a negative for prospective future tenants.
We originally bought the place in 2009 for our daughter, who was going to school in Boston. She shared it with a roommate, who paid rent. When D left, we continued to rent the place out. It’s been a great steady income stream with few problems (even this isn’t so terrible). We have a great real estate agent who doesn’t exactly manage the place, but gets all our tenants for us, and screens them quite well. You’ve all given me a lot to think about. Thanks!
I’m sure you are in the clear. Very little has to meet current code if it was compliant when it was built. Just unusual to have such a narrow door into a kitchen.
@HotCanary - something tells me you are not a slumlord. 
Good luck with the adventures in range replacement. We had an odd size fridge space in House1, and finding a fridge was a pita to begin with. There were a whopping 2 models that fit that space back in 1999. Thank goodness there are about 5 or 7 that do now. 
I faced a similar issue with a washer and dryer inside my master closet. The washer broke, and a new one was delivered, but it couldn’t be installed because the closet doorway was way smaller than the standard size appliances. We tried everything–removing door, trim,etc. I had to leave both washers where they were until I had the doorway enlarged (which wasn’t too expensive. …house about 20 years old/nothing fancy).No idea how or why this happened. I really wanted to call the previous owner for an explanation. It made no sense. Good luck!
Any chance there is a window in the kitchen wide enough to haul the old one out and new one in? I am having visions of lifting a piano into an apartment.
@BunsenBurner Ha! I was actually a little afraid that I would be perceived as a slumlord! So funny that you used that same word! It’s a really nice apartment, in a beautiful old building, very safe and clean, with a great condo association.We bought it because we were roped into a rat infested place when D was a freshman, and we figured it would be smarter to buy a nice place if we could.
@jym626 There is a door onto a fire escape, but there’s no easy access to the courtyard, if I should even call it that. It’s not from the parking lot, but a kind of unused green space that has no vehicle access. And guess what? We didn’t measure that door! We’d probably have to remove the door and moldings to get the range in. It might work, but the whole scenario seems way beyond what’s necessary. The building was erected in 1900, I believe.