Number Gossip

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Unique Properties of 33

A web page about 33: 33 Mysteries Home Page

Common Properties of 33

Composite

A positive integer greater than 1 that is not prime is called composite.

Composite numbers are opposite to prime numbers.

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28,
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32,
33,
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35,
36,
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Deficient

The number n is deficient if the sum of all its positive divisors except itself is less than n.

Compare with perfect and abundant numbers.

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29,
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35,
37,
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Evil

The number n is evil if it has an even number of 1's in its binary expansion.

Guess what odious numbers are.

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27,
29,
30,
33,
34,
36,
39,
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Lucky

To build the lucky number sequence, start with natural numbers. Delete every second number, leaving 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, ... . The second number remaining is 3, so delete every third number, leaving 1, 3, 7, 9, 13, 15, 19, 21, ... . The next number remaining is 7, so delete every 7th number, leaving 1, 3, 7, 9, 13, 15, 21, ... . The next number remaining is 9, so delete every ninth number, etc.

Those numbers were lucky they weren't crossed out.

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21,
25,
31,
33,
37,
43,
49,
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Odd

A number is odd if it is not divisible by 2.

Numbers that are not odd are even. Compare with another pair -- evil and odious numbers.

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27,
29,
31,
33,
35,
37,
39,
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Palindrome

A palindrome is a number that reads the same forward or backward.

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9,
11,
22,
33,
44,
55,
66,
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Square-free

A number is said to be square-free if its prime decomposition contains no repeated factors.

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29,
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31,
33,
34,
35,
37,
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Tanya Khovanova

Number Gossip

Unique Properties of 33

Common Properties of 33