Answer:
163
Step-by-step explanation:
So n=391.
This means p=23 and q=17 where p*q=n.
[tex] \lambda (391)=lcm(23-1,17-1)=lcm(22,16)=2*8*11=16*11=176. [/tex]
We want to choose e so that e is between 1 and 176 and the gcd(e,176)=1.
There is only one number in your list that is between 1 and 176... Hopefully the gcd(163,176)=1.
It does. See notes below for checking it:
176=2(88)=2(4*22)=2(2)(2)(2)(11)
None of the prime factors of 176 divide 163 so we are good.
The answer is 163.
