Where does the phone number 3 61 73 come from?

Hello,

I recently had a conflict with someone (I'll spare you the details, in short this person is doing everything to see me) which resulted in a change of my phone number.

I still don't know if it's this person or not: I received a text message from the number 3 61 73 with the message "AD>hello I found your number, If you're available for a meet-up I'm free this week. call me at 08.......09 it's more discreet (0.80E/min) n4 STOP at 36173" (I respected the capitalization etc.).

I would like to know if it's possible to find out how this person could have found my phone number (if it's really what they claim and if it's the person I'm talking about), where this number comes from, what it means (the AD>, n4 STOP etc.) and all that...

I immediately blocked them, took a screenshot of the message with the number, and I didn’t respond.

Thank you in advance for any possible response!