81 (number)
= 81 (number)
{wiki=81_(number)}
The number 81 is an integer that is the square of 9 (since \\(9 \\times 9 = 81\\)). It belongs to various mathematical categories, including being recognized as a composite number, as it has factors other than 1 and itself (specifically, 1, 3, 9, 27, and 81).