214
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Number
$214$ (two hundred and fourteen) is:
- $2 \times 107$
- The $7$th non-square positive integer which cannot be expressed as the sum of a square and a prime:
- $10$, $34$, $58$, $85$, $91$, $130$, $214$, $\ldots$
- The $12$th number after $1$, $3$, $22$, $66$, $70$, $81$, $94$, $115$, $119$, $170$, $210$ whose divisor sum is square:
-
- $\map {\sigma_1} {214} = 324 = 18^2$
- The $13$th positive integer which cannot be expressed as the sum of a square and a prime:
- $1$, $10$, $25$, $34$, $58$, $64$, $85$, $91$, $121$, $130$, $169$, $196$, $214$, $\ldots$
- The $31$st nontotient:
- $\nexists m \in \Z_{>0}: \map \phi m = 214$
- where $\map \phi m$ denotes the Euler $\phi$ function