526

Number
$526$ (five hundred and twenty-six) is:


 * $2 \times 263$


 * The $19$th positive integer which cannot be expressed as the sum of a square and a prime:
 * $1, 10, 25, 34, 58, 64, 85, 91, 121, 130, 169, 196, 214, 226, 289, 324, 370, 400, 526, \ldots$