Numeric Value: 81

The folowing table expresses '81' in various number bases. 'DRx' shows the result of 'digit reducing' resulting in an X-digit long number.

BaseDR7DR6DR5DR4DR3DR2DR1
21010001    11,101
3  10000   1
4   1101  3
5    311101
6    213101
7    144123
8    121 4
9    100 1
10     819
11     74,101
12     69,134
13     639
14     5B,123
15     56B
16     516

Math World

Factors: 34

81 is in the Pythagorean Triple: (81, 3280, 3281).

Physical World

81 is the atomic weight of Thallium (Tl).