690

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Number

$690$ (six hundred and ninety) is:

$2 \times 3 \times 5 \times 23$

The $9$th positive integer after $1$, $7$, $102$, $110$, $142$, $159$, $187$, $381$ the sum of whose divisors is a cube:

$\map {\sigma_1} {690} = 1728 = 12^3$

The $35$th Smith number after $4$, $22$, $27$, $58$, $\ldots$, $576$, $588$, $627$, $634$, $636$, $645$, $648$, $654$, $663$, $666$:

$6 + 9 + 0 = 2 + 3 + 5 + 2 + 3 = 15$

Also see

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