Alessandra is the Italian feminine of Alessandro — from the Greek Alexandros, alexein (to defend) + aner (man). Forbes World's Highest-Paid Models list every year 2008-2017. Carried the Olympic torch in Rio de Janeiro 2016 and walked the opening ceremony as one of Brazil's three flag-bearers. Alessandra Mussolini — Italian politician (granddaughter of Benito).
Alessandra 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 Alessandra reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.