1009
Jump to navigation
Jump to search
Number
$1009$ (one thousand and nine) is:
- The $169$th prime number
- The $1$st prime number which can be expressed in the form $x^2 + n y^2$ for all values of $n$ from $1$ to $10$:
\(\ds 1009\) | \(=\) | \(\ds 15^2 + 1 \times 28^2 = 28^2 + 1 \times 15^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 19^2 + 2 \times 18^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 31^2 + 3 \times 4^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 15^2 + 4 \times 14^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 17^2 + 5 \times 12^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 25^2 + 6 \times 8^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds \ \, 1^2 + 7 \times 12^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 19^2 + 8 \times 9^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 18^2 + 9 \times 5^2\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 3^2 + 10 \times 10^2\) |
- The $34$th emirp after $13$, $17$, $31$, $37$, $\ldots$, $733$, $739$, $743$, $751$, $761$, $769$, $907$, $937$, $941$, $953$, $967$, $971$, $983$, $991$
Also see
Sources
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $1009$