When they are coprime, a simple way to find LCM is to just multiply them together.
This means that 29 multiplied by something is equal to 638.
Divide it and we will get the number.
Therefore, the other number is 22.
1 11, 29 (both are prime numbers)
⇒2×11×29 is the prime factorizaion of 638.
Therefore, answer is correct.