Euler Phi Function of 87

Example of Euler $\phi$ Function of Non-Square Semiprime

$\phi \left({87}\right) = 56$

where $\phi$ denotes the Euler $\phi$ Function.

Proof

We have that:

$87 = 3 \times 29$

Thus:

\(\ds \phi \left({87}\right)\)

\(=\)

\(\ds \left({3 - 1}\right) \left({29 - 1}\right)\)

Euler $\phi$ Function of Non-Square Semiprime

\(\ds \)

\(=\)

\(\ds 2 \times 28\)

\(\ds \)

\(=\)

\(\ds 56\)

$\blacksquare$