On which of the following medias does Jacob Sartorius have the least followers?

Explanation

Jacob Sartorius is clearly a SoMe superstar. He has engaged millions of fans all over the World. His Twitter, @jacobsartorius has more than 1.6 million followers. On YouTube, Jacob has around 3 million subscribers. On Instagram, there are over 9 million people following him. 1,2 million like his official Facebook page - and these numbers are constantly growing! Last but not least, on Musical.ly he did engage about 20 million.