Mika has independent roots across cultures: Japanese (美香 — "beautiful fragrance"); Finnish (a short form of Mikael / Michael); and Hebrew (מיכה — "Who is like God," feminine of Micah). Mika Hakkinen is male (Finnish F1 champion). Mika Newton — Ukrainian singer.
Mika 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 Mika reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.