Alright, let's work through 81867791 times 43669137 step by step
81867791 × 43669137 = 43669137 × (81867791)
+ 43669137 × 1 what gives us 43669137
+ 43669137 × 90 giving us 3930222330
+ 43669137 × 700 that results in 30568395900
+ 43669137 × 7000 yielding 305683959000
+ 43669137 × 60000 that results in 2620148220000
+ 43669137 × 800000 producing 34935309600000
+ 43669137 × 1000000 yielding 43669137000000
+ 43669137 × 80000000 which equals 3493530960000000

= 3575095781066367
