Alright, let's work through 20699349 times 36401357 step by step
20699349 × 36401357 = 36401357 × (20699349)
+ 36401357 × 9 giving us 327612213
+ 36401357 × 40 producing 1456054280
+ 36401357 × 300 resulting in 10920407100
+ 36401357 × 9000 giving us 327612213000
+ 36401357 × 90000 producing 3276122130000
+ 36401357 × 600000 that is equal 21840814200000
+ 36401357 × 0000000 that is equal 0
+ 36401357 × 20000000 what gives us 728027140000000

= 753484392616593
