691

Number
$691$ (six hundred and ninety-one) is:


 * The $125$th prime number.


 * The larger of the $8$th pair of primes whose prime gap is $8$:
 * $691 - 683 = 8$


 * The smaller of the $11$th pair of primes whose prime gap is $10$:
 * $701 - 691 = 10$


 * The $7$th candidate Lychrel number.