• 77 can be written using four 4's:
• Deleting all the even digits from 277 = 151115727451828646838272 we obtain a prime (151115775137).
77 is nontrivially palindromic in base 10.
77 is an esthetic number in base 12, because in such base its adjacent digits differ by 1.
It is a cyclic number.
It is a nude number because it is divisible by every one of its digits.
It is an Ulam number.
It is a Duffinian number.
77 is a nontrivial repdigit in base 10.
It is a plaindrome in base 8, base 10, base 13, base 14 and base 16.
It is a nialpdrome in base 9, base 10, base 11, base 12 and base 15.
It is a zygodrome in base 10.
It is a congruent number.
It is a panconsummate number.
It is an amenable number.
77 is a wasteful number, since it uses less digits than its factorization.
77 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 18.
The square root of 77 is about 8.7749643874. The cubic root of 77 is about 4.2543208651.
Adding to 77 its sum of digits (14), we get a triangular number (91 = T13).
Subtracting from 77 its product of digits (49), we obtain a triangular number (28 = T7).
Multiplying 77 by its product of digits (49), we get a palindrome (3773).