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2.4 RSA Encryption

Relative Primality


How many numbers between 1 and 3780 (inclusive) are relatively prime to 3780?

Exercise 1

3780 = 2^2 \cdot 3^3 \cdot 5 \cdot 7, so using the formula for Euler's \Phi function, there are

(4-2) \cdot (27-9) \cdot (5-1) \cdot (7-1) = 864 such numbers.