You've found the prime factorization when all of your factors are prime. They can't be divided into any smaller factors.
Answer:
We first have to find the volume of the cube: (0.3 * 0.3 * 0.3) we then get 0.027, then we plug in the numbers for the density formula. D = 18.954/0.027 will give us 702.
V = (12·15 - 1/2·(12 - 7)·(15 - 5))·8 = 1240 cm³