Alright, let's work through 21383836 times 81671790 step by step
21383836 × 81671790 = 81671790 × (21383836)
+ 81671790 × 6 what gives us 490030740
+ 81671790 × 30 what gives us 2450153700
+ 81671790 × 800 giving us 65337432000
+ 81671790 × 3000 yielding 245015370000
+ 81671790 × 80000 giving us 6533743200000
+ 81671790 × 300000 yielding 24501537000000
+ 81671790 × 1000000 what gives us 81671790000000
+ 81671790 × 20000000 that is equal 1633435800000000

= 1746456163186440
