679

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Number

$679$ (six hundred and seventy-nine) is:

$7 \times 97$

The smallest number having a multiplicative persistence of $5$.

The $32$nd number whose divisor sum is square:

$\map {\sigma_1} {679} = 784 = 28^2$

Arithmetic Functions on $679$

\(\ds \map {\sigma_1} { 679 }\)

\(=\)

\(\ds 784\)

$\sigma_1$ of $679$

Also see

• Previous  ... Next: Smallest Arguments for given Multiplicative Persistence
• Previous  ... Next: Numbers whose Divisor Sum is Square

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $679$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $679$