Icloud account

They are scam calls. Hang up or don't answer. Also see: Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

That is the number that they display on the caller id screen. Almost all scam calls spoof the caller id number in order to make it more likely that people will answer. It is not the number that is actually originating the call. Caller ID numbers are easily spoofed. Apple never calls to say that an account is hacked.