Alright, let's work through 21408692 times 31210019 step by step
21408692 × 31210019 = 31210019 × (21408692)
+ 31210019 × 2 which equals 62420038
+ 31210019 × 90 resulting in 2808901710
+ 31210019 × 600 what gives us 18726011400
+ 31210019 × 8000 which equals 249680152000
+ 31210019 × 00000 resulting in 0
+ 31210019 × 400000 which equals 12484007600000
+ 31210019 × 1000000 resulting in 31210019000000
+ 31210019 × 20000000 giving us 624200380000000

= 668165684085148
