Numberphile is a YouTube math focused channel that produces a new video approximately once each week that focuses on numbers of some type.
Numberphile is an interesting channel, but not one of my favorites. My preference is more science focused videos and without an unlimited amount of time in a day, I simply don't have the time to keep up on these videos. However, if you have a strong interest in math you should definitely check this channel out. You may have a much greater interest in it than I do and find it very worthwhile.