You may be able to do that on your mac:
Wi-Fi Scanner Tool is Native in Mac OS X, Here’s How to Use it
There are numerous tools to do this on on both Android and iOS. iStumbler is once such tool.
Most wi-fi routers allow you to configure which channel they'll use, so you're likely to run into any of 11 channels in the US and any of 13 in Europe in the 2.4 GHz band and any of 23 in the 5GHz band in the US. I don't know what's happening in Europe for 5GHz.
There's an channel overlap issue on the 2.4gHz band, so if there is an adjacent channel transmitter it might be advantageous to change channels if your throughput sucks. That's one reason why there are so many wi-fi analyzers in app stores. You run it on your phone and they'll show the transmitters and give you an idea of their overlap.