Margarita is the Spanish form of Margaret — from the Greek margarites ("pearl") — and also the Spanish-Mexican word for daisy. Margarita Carmen Cansino — Rita Hayworth's birth name. Saint Margaret of Cortona is venerated as Santa Margarita.
Margarita 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 Margarita reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.