Sothy is from the Khmer / Cambodian សុធី (Sothy — peace, radiant brightness) — from Pali-Sanskrit sōti (purity, brightness). Sothy is one of the Cambodian feminine + unisex names — central to traditional Khmer Theravada Buddhist heritage.
Sothy 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 Sothy reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.