291

Number
$291$ (two hundred and ninety-one) is:


 * $3 \times 97$


 * The $43$rd happy number after $1, 7, 10, 13, 19, 23, \ldots, 188, 190, 192, 193, 203, 208, 219, 226, 230, 236, 239, 262, 263, 280$:
 * $291 \to 2^2 + 9^2 + 1^2 = 4 + 81 + 1 = 86 \to 8^2 + 6^2 = 64 + 36 = 100 \to 1^2 + 0^2 + 0^2 = 1$