1105

Number
$1105$ (one thousand, one hundred and five) is:


 * $5 \times 13 \times 17$


 * The $4$th Poulet number after $341$, $561$, $645$:
 * $2^{1105} \equiv 2 \pmod {1105}$: $1105 = 5 \times 13 \times 17$


 * The $2$nd Carmichael number after $561$:
 * $\forall a \in \Z: a \perp 1105: a^{1104} \equiv 1 \pmod {1105}$


 * The magic constant of the order $13$ magic square:
 * $1105 = \dfrac {13 \left({13^2 + 1}\right)} 2$