My guess is that you switched the latitude and the longitude. Looking at the coordinates you gave, I assume that you wanted the latitude to be 43.620416, and the longitude to be 7.065491, so that the point would be in France. However, according to the doc, GeoDjango expects the first value to be the longitude, and the second one the latitude.
Switching these two coordinates may have caused GeoDjqngo to get lost with the values you gave. (4856153.76879, 788079.64711) may then be some internal representation of the point you gave.