I read on the European Pirate Party Wikipedia article that they received 868 069 votes. I would like to compare this figure with the total votes cast for all parties. The EU Parliament Results only shows the turnout in terms of percentages.
The total turnout for the 2014 EU election of was 42.54%.
The total population of the EU in 2014 is 507,416,607 (estimated provisional)
I wasn't able to find out an breakdown of ages groups which separated the ages at exactly voting age - so the best estimate I can give is 15% which are under 14 and of the 15-24 age group (11%) I'll just add 5% so we get a nice even number of 20% of Europeans who are not eligible to vote due to age restrictions.
That leaves about 400.000.000 European (a number also seen on the official elections page) who could have voted - with the turnout of 42.54% that comes out as 170,160,000.
I think I just found what you were looking for :
Regitered voters : 396.104.240
Voters : 168.818.151
Turnout : 42,61%
Valid votes : 163.551.013
The European Pirate Party got no votes - the national parties did. The only "successful" one would be the German Pirate Party, specifically 424,510 (1.45%). They got one MEP (Julia Reda). EU Parliament members are voted separately for each state.
A few other national pirate parties also participated as can be seen here. You can find a table of votes and the relevant percentages.