4. (10 points) The product of three consecutive natural numbers is 120, their sum is $\qquad$
【Analysis】First, decompose 120 into prime factors, and divide the prime factors into three groups so that the product of the numbers in each group results in three consecutive natural numbers, which will give us the solution.

【Solution】Solution: $120=2 \times 2 \times 2 \times 3 \times 5=(2 \times 2) \times(2 \times 3) \times 5$,
$$
2 \times 2=4,2 \times 3=6,5 \text {, }
$$

That is, the product of three consecutive natural numbers is 120, these three numbers are $4, 5, 6$,
Therefore, the sum is: $4+5+6=15$.
Hence, the answer is: 15.
【Comment】This problem tests the flexible application of decomposing composite numbers into prime factors to solve more complex problems.