21-3165844 is a harassing call.

Blackout Interception

Open Tencent Mobile Manager-Harassment Interception-Phone or SMS, or select the interception mode (such as black-and-white list) in the settings

You can set your own blacklist, and add unwanted phone numbers to the blacklist to achieve accurate interception; At the same time, it can also set the content of spam messages that are often received as keywords, which can greatly increase the accuracy of spam message interception.