441

Number
$441$ (four hundred and forty-one) is:
 * $3^2 \times 7^2$


 * The $21$st square number after $1$, $4$, $9$, $16$, $25$, $36$, $\ldots$, $225$, $256$, $289$, $324$, $361$, $400$:
 * $441 = 21 \times 21$


 * The sum of the first $6$ cubes:
 * $441 = 1^3 + 2^3 + 3^3 + 4^3 + 5^3 + 6^3$


 * The $36$th powerful number after $1$, $4$, $8$, $9$, $16$, $25$, $\ldots$, $289$, $324$, $343$, $361$, $392$, $400$, $432$:
 * $441 = 3^2 \times 7^2$