Alright, let's work through 12639142 times 68191026 step by step
12639142 × 68191026 = 68191026 × (12639142)
+ 68191026 × 2 which equals 136382052
+ 68191026 × 40 giving us 2727641040
+ 68191026 × 100 yielding 6819102600
+ 68191026 × 9000 resulting in 613719234000
+ 68191026 × 30000 that equals 2045730780000
+ 68191026 × 600000 which equals 40914615600000
+ 68191026 × 2000000 yielding 136382052000000
+ 68191026 × 10000000 producing 681910260000000

= 861876060739692
