2, 3, 6, 7, 14, 21, 42, 43, 86, 129, 258, 301, 602, 903
No. Some proper factors are prime.
No, no prime number has proper factors.
1 doesn't have proper factors.
One has no proper factors.
The proper factors of 26 are 2 and 13
Prime numbers don't have proper factors.
The proper factors of 35 are 5 and 7.
Prime numbers don't have proper factors.
The proper factors of 220 are 2,4,5,10,11,20,22,44,55,110
Prime numbers don't have proper factors.
The proper factors of 22 are 2 and 11.
Prime numbers don't have proper factors.