Hyphens and Numbers
Numbers between twenty-one and ninety-nine should be hyphenated when they’re spelled out.
Hyphen in Compound Adjective With Numbers
When numbers are used as the first part of a compound adjective, use a hyphen to connect them to the noun that follows them. This way, the reader knows that both words function like a unit to modify another noun. This applies whether the number is written in words or in digits.
However, a hyphen is not required if the number is the second word in the compound adjective.
Hyphen In Compound Adjective With Fractions
When using a fraction (e.g. half or quarter) as part of a compound adjective, it should be hyphenated so the reader understands which fraction is modifying which noun.
from Grammarly Blog https://www.grammarly.com/blog/hyphen-in-compound-adjective-with-numbers/