23,209
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Number
$23 \, 209$ (twenty-three thousand, two hundred and nine) is:
- The $2591$st prime number
- The index of the $26$th Mersenne prime after $2$, $3$, $5$, $7$, $13$, $\ldots$, $2203$, $2281$, $3217$, $4253$, $4423$, $9689$, $9941$, $11 \, 213$, $19 \, 937$, $21 \, 701$:
- $M_{23 \, 209} = 2^{23 \, 209} - 1 \approx 4 \cdotp 029 \times 10^{6986}$
Also see
- Previous ... Next: Index of Mersenne Prime
- Previous ... Next: Prime Number
Historical Note
The Mersenne number $M_{23 \, 209} = 2^{23 \, 209} - 1$ was demonstrated to be a Mersenne prime on $9$ February $1979$ by Landon Curt Noll, using the same CDC-CYBER-174 that he and Laura Nickel used to discover the primality of $M_{21 \, 701}$.
It took the computer $8$ hours to check the number.
$2$ weeks later, David Slowinski used a CRAY-1 supercomputer to check the result, and it took $7$ minutes.
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $2^{23209} - 1$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $2^{23,209} - 1$