1782
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Number
$1782$ (one thousand, seven hundred and eighty-two) is:
- $2 \times 3^4 \times 11$
- $3$ times the sum of all the $2$-digit integers that can be formed from its digits:
- $1782 = 3 \times 594 = 3 \times \paren {17 + 18 + 12 + 71 + 78 + 72 + 81 + 87 + 82 + 21 + 27 + 28}$
- The $27$th heptagonal number after $1$, $7$, $18$, $34$, $55$, $81$, $112$, $\ldots$, $874$, $970$, $1071$, $1177$, $1288$, $1404$, $1525$, $1651$:
- $1782 = \ds \sum_{k \mathop = 1}^{27} \paren {5 k - 4} = \dfrac {27 \paren {5 \times 27 - 3} } 2$
Also see
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $1782$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $1782$