Old Number 4

This is a shot of a rusty hub of an ancient  wheel. I like the macro and selective focus of this image.  I was looking for an Old Nunber 7, so I could relate a cool Jack Daniels Story, now I must only relate some curious Math Facts about the incredible Four!

Four is the smallest composite number, its proper divisors being 1 and 2. Four is also a highly composite number. The next highly composite number is 6.

Four is the second square number, the second centered triangle number. Four is the smallest squared prime and the only even number in this form. It has an aliquot sum of 3 which is itself prime. The aliquot sequence of 4 has 4 members (4, 3, 1, 0) and is accordingly the first member of the 3-aliquot tree.

Only one number has an aliquot sum of 4 and that is squared prime 9. The prime factorization of  four is two times two. OK, enough already!

One response

  1. Tom

    love rust

    April 10, 2011 at 7:45 am

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