Here's Herodotus:

When these numbers are added to the numbers from Asia, the sum total of fighting men is two million, six hundred and forty-one thousand, six hundred and ten.

And

This then is the number of soldiers. As for the service-train which followed them and the crews of the light corn-bearing vessels and all the other vessels besides which came by sea with the force, these I believe to have been not fewer but more than the fighting men. [2] Suppose, however, that they were equal in number, neither more nor fewer. If they were equal to the fighting contingent, they made up as many tens of thousands as the others. The number, then, of those whom Xerxes son of Darius led as far as the Sepiad headland and Thermopylae was five million, two hundred and eighty-three thousand, two hundred and twenty.