Alright, let's work through 3671 times 1221 step by step
3671 × 1221 = 1221 × (3671)
+ 1221 × 1 producing 1221
+ 1221 × 70 which equals 85470
+ 1221 × 600 giving us 732600
+ 1221 × 3000 yielding 3663000

= 4482291
