Proper factors are just like regular factors, except they don't include 1 and the number itself.
No. Some proper factors are prime.
No, no prime number has proper factors.
One has no proper factors.
1 doesn't have proper factors.
Prime numbers don't have proper factors.
The proper factors of 35 are 5 and 7.
The proper factors of 26 are 2 and 13
Prime numbers don't have proper factors.
Prime numbers don't have proper factors.
Zero doesn't have any proper factors.
Prime numbers don't have proper factors.
The proper factors of 220 are 2,4,5,10,11,20,22,44,55,110