Alright, let's work through 21489990 times 64689586 step by step
21489990 × 64689586 = 64689586 × (21489990)
+ 64689586 × 0 giving us 0
+ 64689586 × 90 yielding 5822062740
+ 64689586 × 900 that equals 58220627400
+ 64689586 × 9000 that results in 582206274000
+ 64689586 × 80000 which equals 5175166880000
+ 64689586 × 400000 giving us 25875834400000
+ 64689586 × 1000000 what gives us 64689586000000
+ 64689586 × 20000000 that results in 1293791720000000

= 1390178556244140
