Euler's totient φ(n) counts how many positive integers below n are coprime to n.
Try it
φ(10)
Coprime to 10 below it: 1, 3, 7, 9. So φ(10) = 4.
Used in RSA encryption — and famously, e^(iπ) + 1 = 0 lives in Euler's universe.
Euler's totient φ(n) counts how many positive integers below n are coprime to n.
φ(10)
Coprime to 10 below it: 1, 3, 7, 9. So φ(10) = 4.
Used in RSA encryption — and famously, e^(iπ) + 1 = 0 lives in Euler's universe.