Alright, let's work through 4151 times 5121 step by step
4151 × 5121 = 5121 × (4151)
+ 5121 × 1 producing 5121
+ 5121 × 50 that is equal 256050
+ 5121 × 100 yielding 512100
+ 5121 × 4000 that equals 20484000

= 21257271
