Mahtab (مهتاب) is the Persian compound of mah (moon) and tab (light, radiance) — meaning "moonlight." Widely used in Iran and Afghanistan.
Mahtab Keramati (born 1972), the Iranian actress, is a contemporary bearer.
Mahtab 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 Mahtab reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.