341

Number
$341$ (three hundred and forty-one) is:


 * $11 \times 31$


 * The $1$st Poulet number:
 * $2^{341} \equiv 2 \pmod {341}$: $341 = 11 \times 31$


 * The $4$th Fermat pseudoprime to base $4$ after $15$, $85$, $91$:
 * $4^{341} \equiv 4 \pmod {341}$


 * The $11$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $96$, $133$, $176$, $225$, $280$:
 * $341 = 1 + 7 + 13 + 19 + 25 + 31 + 37 + 43 + 49 + 55 = \ds \sum_{k \mathop = 1}^n \paren {6 k - 5} = 11 \paren {3 \times 11 - 2}$

Also see