Perfect numbers are numbers that are equal to the sum of their positive divisors except itself. The smallest perfect number is 6. The positive divisors of 6: The sum of the divisors of 1, 2, 3 and 6 except itself: 1 + 2 + 3 = 6 and 6 is a perfect number. Likewise, the positive divisors of 28: 1, 2, 4, 7, 14, 28 is the sum of the divisors except itself: 1 + 2 + 4 + 7 + 14 = 28 and 28 is a perfect number. So, write a MATLAB function that checks if a given number is a perfect number..