Alright, let's work through 21003551 times 17263436 step by step
21003551 × 17263436 = 17263436 × (21003551)
+ 17263436 × 1 that is equal 17263436
+ 17263436 × 50 producing 863171800
+ 17263436 × 500 resulting in 8631718000
+ 17263436 × 3000 giving us 51790308000
+ 17263436 × 00000 that results in 0
+ 17263436 × 000000 that is equal 0
+ 17263436 × 1000000 which equals 17263436000000
+ 17263436 × 20000000 yielding 345268720000000

= 362593458461236
