Alright, let's work through 20538375 times 21047242 step by step
20538375 × 21047242 = 21047242 × (20538375)
+ 21047242 × 5 that is equal 105236210
+ 21047242 × 70 which equals 1473306940
+ 21047242 × 300 yielding 6314172600
+ 21047242 × 8000 producing 168377936000
+ 21047242 × 30000 that equals 631417260000
+ 21047242 × 500000 yielding 10523621000000
+ 21047242 × 0000000 which equals 0
+ 21047242 × 20000000 giving us 420944840000000

= 432276148911750
