Nato is from the Georgian ნათო (Nato) — diminutive of Natela (light) — Georgian feminine name. Nato is one of the Georgian feminine names — central to traditional Georgian Orthodox heritage.
Nato 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 Nato reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.