106

Number
$106$ (one hundred and six) is:


 * $2 \times 53$


 * The $34$th semiprime:
 * $106 = 2 \times 53$


 * The $2$nd of the $1$st ordered triple of consecutive integers that have Euler $\phi$ values which are strictly increasing:
 * $\map \phi {105} = 48$, $\map \phi {106} = 52$, $\map \phi {107} = 106$


 * The $3$rd of the $2$nd ordered quadruple of consecutive integers that have divisor sums which are strictly decreasing:
 * $\map {\sigma_1} {104} = 210, \ \map {\sigma_1} {105} = 192, \ \map {\sigma_1} {106} = 162, \ \map {\sigma_1} {107} = 108$

Also see