170

Number
$170$ (one hundred and seventy) is:


 * $2 \times 5 \times 17$


 * The $23$rd nontotient:
 * $\nexists m \in \Z_{>0}: \phi \left({m}\right) = 170$
 * where $\phi \left({m}\right)$ denotes the Euler $\phi$ function


 * The $15$th noncototient after $10$, $26$, $34$, $50$, $52$, $58$, $86$, $100$, $116$, $122$, $130$, $134$, $146$, $154$:
 * $\nexists m \in \Z_{>0}: m - \phi \left({m}\right) = 170$
 * where $\phi \left({m}\right)$ denotes the Euler $\phi$ function


 * The $10$th number after $1, 3, 22, 66, 70, 81, 94, 115, 119$ whose $\sigma$ value is square:


 * The $7$th positive integer after $50, 65, 85, 125, 130, 145$ which can be expressed as the sum of two square numbers in two or more different ways:
 * $145 = 12^2 + 1^2 = 9^2 + 8^2$