Numeric Value: 91

The folowing table expresses '91' in various number bases. 'DRx' shows the result of 'digit reducing' resulting in an X-digit long number.

BaseDR7DR6DR5DR4DR3DR2DR1
21011011   101101
3  10101  101
4   1123 13,101
5    331123
6    231101
7    160101
8    133 7
9    111 3
10     91,101
11     83,101
12     77,123
13     707
14     67D
15     617
16     5B,101

Math World

Factors: 7 * 13

91 is in the Pythagorean Triples: (60, 91, 109), (91, 4140, 4141).

91 is the sum of the counting numbers from 1 to 13 (See 'The Sum/Product of the First N Counting Numbers').

Physical World

91 is the atomic weight of Protactinium (Pa).