My Erdös number is 3. I co-authored papers with Yaacov Yesha (Mutation Operators for Specifications 2000 and Testing with Model Checker: Insuring Fault Visibility 2003), who collaborated with Aviezri S. Fraenkel, who collaborated with Paul Erdös.
Those who wrote a joint paper with Paul Erdös have Erdös number 1. Those who have collaborators with Erdös number 1 have Erdös number 2. Those who have collaborators with Erdös number 2 have Erdös number 3, and so forth.
You can find out more about Paul Erdös and get the names of those with Erdös numbers 1 and 2.
There is actually a Hungarian double acute accent or Hungarian umlaut over the o. I represent it by the ordinary two-dot umlaut available in html, since the true diacritic mark isn't visible in some browsers. Here is what it looks like if your browser supports it: Erdős. (HTML: Erdős)
In January 2006 I found I have an Erdös number of 3, not 4 through Paul Ammann.
Maybe its not too late to an Erdös number of 1.