Euler Phi Function of 1257

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

$\phi \left({1257}\right) = 836$

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

Proof

We have that:

$1257 = 3 \times 419$

Thus:

\(\ds \phi \left({1257}\right)\)

\(=\)

\(\ds \left({3 - 1}\right) \left({419 - 1}\right)\)

Euler $\phi$ Function of Non-Square Semiprime

\(\ds \)

\(=\)

\(\ds 2 \times 418\)

\(\ds \)

\(=\)

\(\ds 2 \times \left({2 \times 11 \times 19}\right)\)

\(\ds \)

\(=\)

\(\ds 836\)

$\blacksquare$