559

Number
$559$ (five hundred and fifty-nine) is:


 * $13 \times 43$


 * The $7$th and last positive integer after $79$, $159$, $239$, $319$, $399$, $479$ which cannot be expressed as the sum of fewer than $19$ fourth powers:
 * $559 = 15 \times 1^4 + 2 \times 2^4 + 2 \times 4^4$
 * or:
 * $559 = 9 \times 1^4 + 4 \times 2^4 + 6 \times 3^4$