Alright, let's work through 20730991 times 18880749 step by step
20730991 × 18880749 = 18880749 × (20730991)
+ 18880749 × 1 producing 18880749
+ 18880749 × 90 yielding 1699267410
+ 18880749 × 900 which equals 16992674100
+ 18880749 × 0000 giving us 0
+ 18880749 × 30000 what gives us 566422470000
+ 18880749 × 700000 what gives us 13216524300000
+ 18880749 × 0000000 that equals 0
+ 18880749 × 20000000 yielding 377614980000000

= 391416637592259
