It's true, the Greek government doesn't know how many civil servants there are in Greece. We are supposed to have ca. 550,000 civil servants earning an average EUR 2,725 per month. Now, based on my trusty EU KLEMS data, I think it's almost twice that much if we count all of the employees in education, health and other community and social services, as the total had already reached 1,024,000 by 2007. Total payroll for these sectors was EUR 30bn in the same year. That worked out to EUR 2,100 per month (assuming 14 wages).
Of course not all of the employment in these sectors is linked to the public sector (whether directly or indirectly), but I suspect my total is closer to the truth than the government's.