21,679

Number
$21 \, 679$ (twenty-one thousand, six hundred and seventy-nine) is:


 * $7 \times 19 \times 163$


 * The $21$st non-square positive integer, and largest known, which cannot be expressed as the sum of a square and a prime:
 * $10, 34, 58, 85, 91, 130, 214, 226, 370, 526, 706, 730, 771, 1255, 1351, 1414, 1906, 2986, 3676, 9634, 21 \, 679$