676

Number
$676$ (six hundred and seventy-six) is:
 * $2^2 \times 13^2$


 * The $26$th square number after $1$, $4$, $9$, $16$, $25$, $36$, $\ldots$, $361$, $400$, $441$, $484$, $529$, $576$, $625$:
 * $676 = 26 \times 26$


 * The $45$th powerful number after $1$, $4$, $8$, $9$, $16$, $25$, $\ldots$, $400$, $432$, $441$, $484$, $500$, $512$, $529$, $576$, $625$, $648$, $675$:
 * $676 = 2^2 \times 13^2$


 * The only known such pair whose second element is even.


 * The larger of the $3$rd pair of consecutive powerful numbers:
 * $675 = 3^3 \times 5^2$, $676 = 2^2 \times 13^2$


 * The $22$nd positive integer which cannot be expressed as the sum of a square and a prime:
 * $1$, $10$, $25$, $34$, $58$, $64$, $85$, $91$, $121$, $130$, $169$, $196$, $214$, $226$, $289$, $324$, $370$, $400$, $526$, $529$, $625$, $676$, $\ldots$


 * The first palindromic square with a non-palindromic square root:
 * $676 = 26^2$

Also see