How to block this and other numbers: I've been using Should I Answer to auto-reject. I use pickup/hangup method to protect my voicemail, so that no one can record my voice in the outgoing message. Some other numbers have been calling me as well, not sure if it's the same scammers as this one. 20215285968 (extra numbers in there?) 31555446689, 3526586532, 2065960631.
Also, do NOT answer "yes" to anything. When you're talking to your bank or other personal accounts, it's common for you to answer "yes, that is correct." While I'm not sure if this is a legitimate thing going around, it's better to be safe than sorry. But I've been hearing reports of a scam to get you to say "Yes" in order to be recorded, in order to hijack your personal accounts.