Alright, let's work through 20513971 times 71508231 step by step
20513971 × 71508231 = 71508231 × (20513971)
+ 71508231 × 1 that equals 71508231
+ 71508231 × 70 resulting in 5005576170
+ 71508231 × 900 that results in 64357407900
+ 71508231 × 3000 that is equal 214524693000
+ 71508231 × 10000 giving us 715082310000
+ 71508231 × 500000 yielding 35754115500000
+ 71508231 × 0000000 giving us 0
+ 71508231 × 20000000 that equals 1430164620000000

= 1466917776995301
