5 1 (5 1 wu) is a natural number between 50 and 52. 5 1 is an odd number, which is the sixth Mertzkin number, the sixth pentagonal number, the fifth central pentagonal number and the third octagonal number.
Decomposition factor: 3× 17
Roman numeral: Li
Binary:110011
Octal: 63
Hexadecimal: 33