170

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


 * $2 \times 5 \times 17$


 * 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:
 * $145 = 12^2 + 1^2 = 9^2 + 8^2$


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


 * The $14$th sphenic number after $30$, $42$, $66$, $70$, $78$, $102$, $105$, $110$, $114$, $130$, $138$, $154$, $165$:
 * $170 = 2 \times 5 \times 17$


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


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