206

Number
$206$ (two hundred and six) is:


 * $2 \times 103$


 * The $30$th nontotient:
 * $\nexists m \in \Z_{>0}: \phi \left({m}\right) = 206$
 * where $\phi \left({m}\right)$ denotes the Euler $\phi$ function


 * The $19$th noncototient after $10$, $26$, $34$, $50$, $52$, $58$, $86$, $100$, $116$, $122$, $130$, $134$, $146$, $154$, $170$, $172$, $186$, $202$:
 * $\nexists m \in \Z_{>0}: m - \phi \left({m}\right) = 206$
 * where $\phi \left({m}\right)$ denotes the Euler $\phi$ function


 * The $11$th untouchable number after $2$, $5$, $52$, $88$, $96$, $120$, $124$, $146$, $162$, $188$.


 * The $2$nd positive integer solution after $14$ to $\sigma \left({n}\right) = \sigma \left({n + 1}\right)$:
 * $\sigma \left({206}\right) = 312 = \sigma \left({207}\right)$


 * The $5$th positive integer after $200, 202, 204, 205$ that cannot be made into a prime number by changing just $1$ digit