No problem, we've got 83121824 and 64447639 to multiply
83121824 × 64447639 = 64447639 × (83121824)
+ 64447639 × 4 which equals 257790556
+ 64447639 × 20 what gives us 1288952780
+ 64447639 × 800 yielding 51558111200
+ 64447639 × 1000 resulting in 64447639000
+ 64447639 × 20000 producing 1288952780000
+ 64447639 × 100000 that equals 6444763900000
+ 64447639 × 3000000 that results in 193342917000000
+ 64447639 × 80000000 yielding 5155811120000000

= 5357005306173536
