11,621

Number
$11 \, 621$ (eleven thousand, six hundred and twenty-one) is:


 * The $1398$th prime number


 * The $4$th after $11 \, 593$, $11 \, 597$, $11 \, 617$ of a sequence of consecutive prime numbers all of the form $4 n + 1$:
 * $11 \, 621 = 4 \times 2905 + 1$