Notes:

source
reddit

From Redditor Maximinus-thrax

• The Diameter:

• Large ball: ~276 pixels
• Small ball: ~2.5 pixels

• The Radius:

Large ball: ~138
Small ball: ~1.25

• The Volume:

Large ball = 4/3.PI.r3 = 10,985,340 units
Small ball = 4/3.PI.r3 = 8.16 units

Spheres pack about 62% of their space, so 6,810,911 units:
Number of balls = large volume / small volume = 834,670.

Considering the assumptions made, we are in an order of magnitude!