52

Number
$52$ (fifty-two) is:


 * $2^2 \times 13$


 * The $5$th noncototient after $10, 26, 34, 50$:
 * $\nexists m \in \Z_{>0}: m - \phi \left({m}\right) = 52$
 * where $\phi \left({m}\right)$ denotes the Euler $\phi$ function


 * The $3$rd untouchable number after $2, 5$.