Do you hyphenate numbers?

When you spell out numbers from twenty-one to ninety-nine that consist of more than one word, hyphenate them. For example, write “thirty-six,” not “thirty six.”

But don’t hyphenate terms for larger numbers such as “hundred,” “thousand,” and “million.” For example, write “three thousand four hundred (and) twenty-seven” and “nineteen sixty-eight.” (Such numbers are normally written as numerals anyway: “3,427”; “1968.”)