Seventy-seven

Seventy-seven (77, LXXVII) is a natural number following seventy-six and preceding seventy-eight. It is the sum of three squares, 4² + 5² + 6², as well as the sum of the first seven prime numbers, but it is itself a composite number with the divisors being 7 and 11. Its factorization is:

Seventy-seven is also:

• The atomic number of iridium.
• The designation of Interstate 77, a freeway that runs from South Carolina to Ohio.

This article is about the number. For the year AD 77, see 77.