Kateri is the Mohawk-Algonquin form of Catherine — adopted by Saint Kateri Tekakwitha (1656-1680), the first Native American Catholic saint.
Kateri is widely used among Native American Catholic families.
Kateri 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 Kateri reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.