Mariem is from the Mauritanian / Sahrawi Hassaniya Arabic Mariem — Mauritanian rendition of Mary / Maryam (Hebrew Miriam — beloved, sea of bitterness). Mariem is one of the Mauritanian + Sahrawi + Maghrebi feminine names — central to traditional Sunni Muslim heritage.
Mariem 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 Mariem reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.