# Divisors of the Positive Integer 21

1, 3, 7, 21## Sum of all the Divisors of 21, including itself

32## Sum of the Proper Divisors of 21

11## Properties of the number 21

The integer 21 is an**odd**number.

The integer 21 is a

**Composite**number.

11 is

*less than*21, so 21 is a

**deficient**number.

## The number 21 as a Roman Numeral

**XXI**

## The number 21 in various Numeral Systems

Base |
Representation |
---|---|

2: | 10101 |

3: | 210 |

4: | 111 |

5: | 41 |

6: | 33 |

7: | 30 |

8: | 25 |

9: | 23 |

10: | 21 |

11: | 1A |

12: | 19 |

13: | 18 |

14: | 17 |

15: | 16 |

16: | 15 |

17: | 14 |

18: | 13 |

19: | 12 |

20: | 11 |

21: | 10 |

22: | L |

23: | L |

24: | L |

25: | L |

26: | L |

27: | L |

28: | L |

29: | L |

30: | L |

31: | L |

32: | L |

33: | L |

34: | L |

35: | L |

36: | L |