Alright, let's work through 21099854 times 40107802 step by step
21099854 × 40107802 = 40107802 × (21099854)
+ 40107802 × 4 that is equal 160431208
+ 40107802 × 50 that equals 2005390100
+ 40107802 × 800 that is equal 32086241600
+ 40107802 × 9000 giving us 360970218000
+ 40107802 × 90000 that equals 3609702180000
+ 40107802 × 000000 that is equal 0
+ 40107802 × 1000000 that results in 40107802000000
+ 40107802 × 20000000 that results in 802156040000000

= 846268766460908
