945

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Number

$945$ (nine hundred and forty-five) is:

$3^3 \times 5 \times 7$

The $1$st odd abundant number:

$\map {\sigma_1} {945} - 945 = 975 > 945$

The $14$th primitive abundant number after $20$, $70$, $88$, $104$, $272$, $304$, $368$, $464$, $550$, $572$, $650$, $748$, $836$:

$1 + 3 + 5 + 7 + 9 + 15 + 21 + 27 + 35 + 45 + 63 + 105 + 135 + 189 + 315 = 975 > 945$

The $19$th primitive semiperfect number after $6$, $20$, $28$, $88$, $104$, $272$, $304$, $350$, $368$, $464$, $490$, $496$, $550$, $572$, $650$, $748$, $770$, $910$:

$945 = 1 + 5 + 7 + 9 + 15 + 21 + 35 + 45 + 63 + 105 + 135 + 189 + 315$

Arithmetic Functions on $945$

\(\ds \map {\sigma_0} { 945 }\)

\(=\)

\(\ds 16\)

$\sigma_0$ of $945$

\(\ds \map \phi { 945 }\)

\(=\)

\(\ds 432\)

$\phi$ of $945$

\(\ds \map {\sigma_1} { 945 }\)

\(=\)

\(\ds 1920\)

$\sigma_1$ of $945$

Also see

• Primitive Semiperfect Number: 945

• Previous  ... Next: Primitive Abundant Number
• Previous  ... Next: Primitive Semiperfect Number

• Next: Sequence of Odd Abundant Numbers

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $945$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $945$