1387

Number
$1387$ (one thousand, three hundred and eighty-seven) is:
 * $19 \times 73$


 * The $22$nd centered hexagonal number after $1$, $7$, $19$, $37$, $61$, $91$, $127$, $\ldots$, $817$, $919$, $1027$, $1141$, $1261$:
 * $1387 = \displaystyle 1 + \sum_{k \mathop = 1}^{22 - 1} 6 k = 22^3 - 21^3$


 * The $5$th Poulet number after $341$, $561$, $645$, $1105$:
 * $2^{1387} \equiv 2 \pmod {1387}$: $1387 = 19 \times 73$