He has 6 paternal cousins of which 4 are royal, and 2 are common.
He has 12 maternal first cousins of which non are royal.
He has 49 second cousins,
He has 203 third cousins.
He has 385 fourth cousins.
I am not counting 1st, 2nd, 3rd , 4th cousins generations removed.
A 17th cousin one generation removed is President Barack Obama who was not invited to his wedding.
Of the 10 monarchs in Europe, here is there relationship to Queen Elizabeth.
King Harald V Norway 2nd cousin via King Edward VII
Queen Margrethe II Denmark 3rd cousin via Christian IX of Denmark
King Carl XVI Gustaf Sweden 3rd cousin via Queen Victoria
King Juan Carlos I Spain 3rd cousin via Queen Victoria
King Albert II Belgium 3rd cousin via Christian IX of Denmark
Grand Duke Henri Luxembourg 3rd cousin once removed via Christian IX of Denmark
Queen Beatrix Netherlands 5th cousin via Frederick II Eugene, Duke of Württemberg
Prince Hans-Adam II Liechtenstein 7th cousin once removed via John William Friso, Prince of Orange
Prince Albert II Monaco 7th cousin twice removed via John William Friso, Prince of Orange
Just add two times removed to each monarch to get their relationship to Prince William