The number 6 is unique in that 6 = 1+2+3, where 1, 2, and 3 are all of the proper. divisors of 6. The number 28 also shares this property, for 28 = 1+2+4+7+14. These âperfectâ numbers have seen a great deal of mathematical studyâindeed, many of the basic theorems of number theory stem from the investigation of the. Greeks into the problem of perfect and Pythagorean numbers [16].