$3,600 a month is more than enough in most places in the US. Especially if you plan right and have a paid off house in an area with favorable property tax laws when you retire.
I live in an area where $3600/month is more than the median income.
Hell, five years ago, I was supporting myself, my wife and a kid on about something like that.[1] It was rough, but just barely manageable.
[1] "Something like that" because I was making significantly less, but had some familial advantages (I was driving a car in decent condition that I got from parents when I was younger, parents bought the kids lots of clothes, and of course I had a safety net, which is huge--not having that would've moved me from constant stress to full blown panic).
Edit: Ohhhh, I forgot the EITC, which makes a big difference. That nudged us a lot closer to that line back then.
Still, where I live, $3600 a month would be fine for a single person who didn't have enormous health care costs (and I know that's a real "aside from that, Mrs. Lincoln?" comment. Retirees are pretty likely to have big medical bills).
I live in Ohio and have paid off my home so for my wife and myself that would be enough. This assumes no expensive medical emergencies, no new cars needed, no significant international travel, etc. Wouldn't be a very luxurious life but we wouldn't starve to death. About all I'm hoping for any longer.
Define "enough". $3600/mo is $43.2k/yr, which is a few k/yr less than the nationwide median income. Keep in mind that in many areas, two wage-earners (that is, $100k+/yr) are required to maintain a middle class standard of living.
It could be pretty adequate if the potential retiree has planned well and has already paid off their home (a typical house payment in an area of the country with a sane cost of living would probably be between $1k-$1.5k). It'd really help to have some decently-sized retirement accounts.
Basically, $3600/mo is adequate maintenance money, but add one or two major expenses to that (like a house, car, or major medical bill), and it gets dicier. If you want to travel during your retirement, or do anything besides buy groceries, you'll need significant savings to draw from.
If the $3600 is what goes into your pocket (I'm not really up on how SS is taxed, since I'm too young to ever have a chance of seeing a dime of it), then yeah, that is a pretty comfortable amount of income in many areas of the US. Assuming you have your mortgage paid off, there are a lot of places in the U.S. where a retired person with that kind of income would have more disposable income than anyone else in the community.
I checked before posting by typing in "median us income": https://archive.is/M05IS . It's $51,939. The difference is that this is median household income, not median personal income. This is the answer I usually see when median income is discussed, and it's really debatable which is the most appropriate to use when discussing what a person can "live off of", though I accept that personal median income is the most direct analog to personal Social Security payments. The real question is whether the OP has a wife that will also be collecting SS.