404

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Number

$404$ (four hundred and four) is:

$2^2 \times 101$

The $8$th even integer after $2$, $4$, $94$, $96$, $98$, $400$, $402$ that cannot be expressed as the sum of $2$ prime numbers which are each one of a pair of twin primes

The $41$st noncototient after $10$, $26$, $34$, $50$, $\ldots$, $344$, $346$, $362$, $366$, $372$, $386$, $394$:

$\nexists m \in \Z_{>0}: m - \map \phi n = 404$

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

Also see

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