6666 has something to do with "Great Shun", which means "Shun Shun Li Shun" and "Good Health". China people think it is an auspicious number. Therefore, the digital red envelope of "health and wellness" can be changed to 6666.
A red envelope refers to a red paper bag wrapped with money. Traditionally, red envelopes, also known as lucky money, are money wrapped in red paper by elders for their children during the Lunar New Year.