Alright, let's work through 21218840 times 77788913 step by step
21218840 × 77788913 = 77788913 × (21218840)
+ 77788913 × 0 what gives us 0
+ 77788913 × 40 giving us 3111556520
+ 77788913 × 800 that equals 62231130400
+ 77788913 × 8000 giving us 622311304000
+ 77788913 × 10000 producing 777889130000
+ 77788913 × 200000 that equals 15557782600000
+ 77788913 × 1000000 resulting in 77788913000000
+ 77788913 × 20000000 what gives us 1555778260000000

= 1650590498720920
