5221
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Number
$5221$ (five thousand, two hundred and twenty-one) is:
- $23 \times 227$
- The $46$th heptagonal number after $1$, $7$, $18$, $34$, $55$, $81$, $112$, $\ldots$, $3744$, $3940$, $4141$, $4347$, $4558$, $4774$, $4995$:
- $5221 = \ds \sum_{k \mathop = 1}^{46} \paren {5 k - 4} = \dfrac {46 \paren {5 \times 46 - 3} } 2$