77777777761 has 2 divisors, whose sum is σ = 77777777762. Its totient is φ = 77777777760.

The previous prime is 77777777719. The next prime is 77777777767. The reversal of 77777777761 is 16777777777.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51701664400 + 26076113361 = 227380^2 + 161481^2 .

It is a cyclic number.

It is not a de Polignac number, because 77777777761 - 2⁷ = 77777777633 is a prime.

It is a nialpdrome in base 10.

It is not a weakly prime, because it can be changed into another prime (77777777767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38888888880 + 38888888881.

It is an arithmetic number, because the mean of its divisors is an integer number (38888888881).

Almost surely, 2^77777777761 is an apocalyptic number.

It is an amenable number.

77777777761 is a deficient number, since it is larger than the sum of its proper divisors (1).

77777777761 is an equidigital number, since it uses as much as digits as its factorization.

77777777761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 242121642, while the sum is 70.

It can be divided in two parts, 7777777776 and 1, that added together give a palindrome (7777777777).

The spelling of 77777777761 in words is "seventy-seven billion, seven hundred seventy-seven million, seven hundred seventy-seven thousand, seven hundred sixty-one".