In some countries there are actually laws about this sort of thing, but in the US I believe you can name your child any tomfool thing you want to. If "weird-symbol-I-choose-to-pronounce-'Prince'" is a name, why not 9?
The name of a 9 sided polygon is Nonagon.
The name of a 9 sided polygon is nonagon or enneagon.
the name of the annoying orange 9 is "annoying saw"
Gloc-9's real name is Aristotle Pollisco.
please name 9 accepted subspecies of giraffe
Fahrenheit 9/11
Nine
I don't believe there is a Greek god whose name has 9 letters and ends with a D. But Aphrodite, a Greek goddess, has 9 letters in her name.
HELLO
9 x 6 = 54
2x2=4+9=13
you can't change your name