During the premiere week, Diablo Immortal was downloaded over 10 million times, according to Blizzard. This is a record for the series. However, it is not surprising, since the game is distributed for free.
The developers did not tell how many downloads were on the mobile version, and how many were on the PC version. But if you believe the statistics of the AppMagic service, in the first seven days Diablo Immortal collected 6.9 million downloads on smartphones (and by today there are already 7.3 million downloads).