I don't think there are any direct estimates. I'm looking in the Inventory of Poleis, which is generally good for this kind of question and at least points to bibliography, but there is not much. They point out that Athens might have fielded 9,000 hoplites at Marathon (but the evidence is rather weak: Nepos, the Suda, and Pausanias -- not exactly Thucydides, there). According to Thucydides (2.13), Athens fielded 13,000 citizen hoplites in 431 at the dawn of the war, with another 16,000 in reserve (3,000 of which were non-citizen metoikoi). We also have estimates of about 50,000-60,000 adult male citizens for this time period (roughly, and before the plague)(Hansen 1988 and Rhodes 1988). (Others put it lower for that time, at about 43,000 in 431 (Gomme 1927)). Call that 26,000 hoplites total, and we only have Thucydides' reputation for general accuracy to rely on. I suspect these figures represented the total potential muster force, not actual dudes with spears, and we have no clue if those figures included "allied" reserves or what. So on all that shaky evidence, you could do a little math and make something like an estimate of adult male population for 490. That also assumes the 9,000 sent to Marathon represented something like a total muster force, and not just what they could round up in the emergency on short notice...