//echo -a $longip(4294967295) -> 255.255.255.255

//echo -a $longip(255.255.255.255)
* /echo: insufficient parameters

Confirmed and an interesting sidenote
//echo -a $longip(255.255.255.255) = * /echo: insufficient parameters
//echo -a $longip(255.255.255) = 4294902015