77961816977 has 10 divisors (see below), whose sum is σ = 85757482290. Its totient is φ = 70874365760.

The previous prime is 77961816949. The next prime is 77961817001.

It is a happy number.

77961816977 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 76377060496 + 1584756481 = 276364^2 + 39809^2 .

It is not a de Polignac number, because 77961816977 - 2⁶ = 77961816913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77961812977) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 2647808 + ... + 2677089.

It is an arithmetic number, because the mean of its divisors is an integer number (8575748229).

Almost surely, 2^77961816977 is an apocalyptic number.

It is an amenable number.

77961816977 is a deficient number, since it is larger than the sum of its proper divisors (7795665313).

77961816977 is an frugal number, since it uses more digits than its factorization.

77961816977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5324941 (or 5324908 counting only the distinct ones).

The product of its digits is 56010528, while the sum is 68.

The spelling of 77961816977 in words is "seventy-seven billion, nine hundred sixty-one million, eight hundred sixteen thousand, nine hundred seventy-seven".