57

Number
$57$ (fifty-seven) is:
 * $3 \times 19$


 * The $18$th Ulam number after $1, 2, 3, 4, 6, 8, 11, 13, 16, 18, 26, 28, 36, 38, 47, 48, 53$:
 * $57 = 4 + 53$