רות = 606

Rus, as her name indicates, possessed many virtues. Implied by the gematria of the name Ruth (רות = 606) is that she was not content to observe only the seven Noahide laws required of a non-Jew. She accepted an additional 606 mitzvos and as a full-fledged Jew kept all 613 mitzvos.

(Me'am Lo'ez)