900

Number
$900$ (nine hundred) is:
 * $2^2 \times 3^2 \times 5^2$


 * The $30$th square number after $1, 4, 9, 16, 25, 36, \ldots, 625, 676, 729, 784, 841$:
 * $900 = 30 \times 30$