206

Number

$206$ (two hundred and six) is:

$2 \times 103$

The $2$nd positive integer solution after $14$ to $\map {\sigma_1} n = \map {\sigma_1} {n + 1}$:

$\map {\sigma_1} {206} = 312 = \map {\sigma_1} {207}$

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

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

The $19$th noncototient after $10$, $26$, $34$, $50$, $52$, $58$, $86$, $100$, $116$, $122$, $130$, $134$, $146$, $154$, $170$, $172$, $186$, $202$:

$\nexists m \in \Z_{>0}: m - \map \phi m = 206$

where $\map \phi m$ denotes the Euler $\phi$ function

The $30$th nontotient:

$\nexists m \in \Z_{>0}: \map \phi m = 206$

where $\map \phi m$ denotes the Euler $\phi$ function