Tupou is the Tongan royal name — the dynastic name of the kings and queens of Tonga since 1845. Queen Sālote Tupou III (1900-1965) was the beloved monarch who ruled for 47 years.
Tupou is widely used in Tonga.
Tupou does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Tupou reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.