1279

Number
$1279$ (one thousand, two hundred and seventy-nine) is:


 * The $207$th prime number


 * The index of the $15$th Mersenne prime after $2$, $3$, $5$, $7$, $13$, $17$, $19$, $31$, $61$, $89$, $107$, $127$, $521$, $607$:
 * $M_{1279} = 2^{1279} - 1 \approx 1 \cdotp 041 \times 10^{385}$


 * The $26$th of $29$ primes of the form $2 x^2 + 29$:
 * $2 \times 25^2 + 29 = 1279$


 * The $2$nd of the $43$rd pair of twin primes:
 * $1279 - 1277 = 2$