FIA just released the driver entry with the driver number.
The FIA entry list in full:
1* Sebastian Vettel, Red Bull
3 Daniel Ricciardo, Red Bull
44 Lewis Hamilton, Mercedes
6 Nico Rosberg, Mercedes
14 Fernando Alonso, Ferrari
7 Kimi Raikkonen, Ferrari
8 Romain Grosjean, Lotus
13 Pastor Maldonado, Lotus
22 Jenson Button, McLaren
20 Kevin Magnussen, McLaren
27 Nico Hulkenberg, Force India
11 Sergio Perez, Force India
99 Adrian Sutil, Sauber
21 Esteban Gutierrez, Sauber
25 Jean-Eric Vergne, Toro Rosso
26 Daniil Kvyat, Toro Rosso
19 Felipe Massa, Williams
77 Valtteri Bottas, Williams
17 Jules Bianchi, Marussia
TBA Max Chilton, Marussia
TBA, Caterham
TBA, Caterham
*For the duration of his F1 career, Vettel chose number 5