It's only a number

via MoMA by Alan McCollum

Wikipedia will tell you (amongst other things)

1. The letters are in alphabetical order
2. It is an octagonal number
3. It is a pentagonal pyramidal number
4. It is the atomic number of Zirconium
5. It's negative is the temperature where Fahrenheit and Celsius scales are equal
6. This many winks is a nap
7. This many days and this many nights means a long time

But it won't tell you what connects it with 20 09 2009 - any ideas?