230

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Number

$230$ (two hundred and thirty) is:

$2 \times 5 \times 23$

The $21$st sphenic number after $30$, $42$, $66$, $70$, $78$, $102$, $105$, $110$, $114$, $130$, $138$, $154$, $165$, $170$, $174$, $182$, $186$, $190$, $195$, $222$:

$230 = 2 \times 5 \times 23$

The $33$rd nontotient:

$\nexists m \in \Z_{>0}: \map \phi m = 230$

where $\map \phi m$ denotes the Euler $\phi$ function

The $37$th happy number after $1$, $7$, $10$, $13$, $19$, $23$, $\ldots$, $130$, $133$, $139$, $167$, $176$, $188$, $190$, $192$, $193$, $203$, $208$, $219$, $226$:

$230 \to 2^2 + 3^2 + 0^2 = 4 + 9 + 0 = 13 \to 1^2 + 3^2 = 1 + 9 = 10 \to 1^2 + 0^2 = 1$

There are $230$ Fedorov groups, if chiral copies are considered distinct.

Also see

• 230 Fedorov Groups where Chiral Pairs are Distinct

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Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $219$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $219$
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): crystallography
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): crystallography