The [data explorer](http://data.stackexchange.com) lets you run queries against a sanitised version of the database. The database is [up to a week out of date](http://meta.stackoverflow.com/a/77176/187228), so it should be good enough for your purposes. [A basic count for superuser](http://data.stackexchange.com/superuser/query/165633/number-of-users) returns 221877 at the time of this post (7th February 2014).