30
It's not entirely clear from the wording of your question what it is you want to know. Seven is a one-digit number. The sum of its digits is 7. Seven has two factors: 1 and 7. That sum is 8.
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.
64
65 has 13 as a factor because 13 divides into 65 evenly with no remainder. The sum of the digits of 65 is 11 because 6 + 5 = 11
2 x 3 x 11 = 66
The number is 875 and its prime factors are 5; 5; 5 & 7.
Try the different numbers - there are only 11 after all - and multiply their digits. Or analyze the factors of the number 21.
50
I am a number less then 100 two of my factors are 3 and 5 my digits are 1 apart
maths
838
28
1
28
37
30
12