turning a page

in just a few days i will be celebrating my 30th birthday. each year as my birthday approaches i like to learn a little bit about the number that will be associated with me for the next 365 days. some ages have real obvious stuff, like 25 is a perfect square. others have mildly obvious stuff, like 27 is a perfect cube. for other ages i have to search a little (read: wikipedia).

as the big 3-0 approaches i thought it was time to get to know that number a little better. obviously 30 ushers in my fourth decade of life, but what else is there about it that makes it special?

it is a primorial number (?)

it is the sum of the sum of the first four squares (1+4+9+16), making it a square pyramidal number

it is the smallest sphenic number, as it is the product of 3 distinct prime numbers (2*3*5)

Adding up a subset of its divisors (e.g., 5, 10 and 15) gives 30, hence 30 is a semi-perfect number

it is also a harshad number (really tough to figure out what a harshad number is)

finally, 30 is the atomic number of zinc

so, there it is. although i won't be able to trust myself anymore, once i'm 30, there will be a lot to be excited about. i've never been a square pyramidal before!