Received automated call saying it was google trying to secure my account from a hack. Left a code for me to use. However, I checked and there was no attempt by google to advise me of the hack.
Its not always a 2 digit number. It depends on what you are trying to do. I was at work trying to get into my email it gave me several options to verify. I asked for the phone call and it gave me a 6 digit number.
And for those others reading if you are not trying to verify your goggle and you get a call from this number, i would check my bank account and credit just in case someone has also gotten a hold to other vital info.