270

Number
$270$ (two hundred and seventy) is:


 * $2 \times 3^3 \times 5$


 * The $5$th Ore number after $1, 6, 28, 140$:
 * $\dfrac {270 \times \tau \left({270}\right)} {\sigma \left({270}\right)} = 6$
 * and the $4$th after $1, 6, 140$ whose divisors also have an arithmetic mean which is an integer:
 * $\dfrac {\sigma \left({270}\right)} {\tau \left({270}\right)} = 45$


 * The $17$th (and last) of the $17$ positive integers for which the value of the Euler $\phi$ function is $72$:
 * $73, 91, 95, 111, 117, 135, 146, 148, 152, 182, 190, 216, 222, 228, 234, 252, 270$

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