+243 For a positive integer $n$, $\phi(n)$ denotes the number of positive integers less than or equal to $n$ that are relatively prime to $n$.
What is $\phi(191)$?
+1233
For a positive integer $n$, $\phi(n)$ denotes the number of positive integers less than or equal to $n$ that are relatively prime to $n$.
What is $\phi(191)$?
191 is a prime number. Therefore, it is relatively prime to every integer less than itself.
You don't count 1, so there are 189 integers (i.e., 2 through 190) relatively prime to 191.
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