Mariah is a 19th-century English spelling of the Hebrew Mary (Miryam). Her 1994 All I Want for Christmas Is You — recorded with Walter Afanasieff in 15 minutes — became the best-selling Christmas single of the 21st century, finally reaching #1 on the Hot 100 in 2019, 25 years after its release.
Mariah 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 Mariah reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.