Who can participate in international math conferences? Who can participate in international conferences in mathematics? 
Does one have to be a mathematician or affiliated as a researcher in a university to participate?
How about Independent researchers (with an undergrad diploma)?
Pay the registration fee and go. Conferences are generally open to all paying customers. In order to give a talk, you will have to submit a paper, extended abstract, or abstract based on the instructions in the call for papers (or participation) and have it reviewed and accepted. But neither kind of participation requires a credential, typically.