310

Number
$310$ (three hundred and ten) is:


 * $2 \times 5 \times 31$


 * The $31$st noncototient after $10, 26, 34, 50, \ldots, 244, 260, 266, 268, 274, 290, 292, 298$:
 * $\nexists m \in \Z_{>0}: m - \phi \left({m}\right) = 310$
 * where $\phi \left({m}\right)$ denotes the Euler $\phi$ function


 * The $47$th happy number after $1, 7, 10, 13, 19, 23, \ldots, 226, 230, 236, 239, 262, 263, 280, 291, 293, 301, 302$:
 * $310 \to 3^2 + 1^2 + 0^2 = 9 + 1 + 0 = 10 \to 1^2 + 0^2 = 1$


 * The $16$th number after $1, 3, 22, 66, 70, 81, 94, 115, 119, 170, 210, 214, 217, 265, 282$ whose $\sigma$ value is square: