No idea, but Mr Co-pilot says
Determining how many US Presidents were "full-blooded Americans" can be a bit tricky, as most presidents have diverse ancestry. However, if we define "full-blooded American" as having ancestors who were among the original settlers of the American colonies, then George Washington is often considered the only president who fits this description, as his family arrived in Virginia in the mid-17th century.
Most presidents have roots tracing back to the British Isles and Western Europe, with many having ancestors who arrived during the colonial period. For example, John Adams and Thomas Jefferson had ancestors who came to America in the early 1600s.