21,576

Number
$21 \, 576$ (twenty-one thousand, five hundred and seventy-six) is:


 * $2^3 \times 3 \times 29 \times 31$


 * The area of The smallest Pythagorean quadrilateral in which the sides of the $4$ right triangles formed by its sides and perpendicular diagonals are all integers

Also see

 * Smallest Pythagorean Quadrilateral with Integer Sides