Which of the following integers is NOT a divisor of x if x = (21)(3^7) – (7)?
Choose one
A) 2
B) 4
C) 7
D) 9
E) 10
(21)(3^7) is divisible by 3 but 7 is not divisible by 3.   Therefore (21)(3^7) - 7 is not divisible by 3 and thus not divisible by 9.   The answer is 9.
<result>D</result>
Which of the following integers is NOT a divisor of x if x = (21)(3^7) – (7)?