77128720867 has 4 divisors (see below), whose sum is σ = 84140422776. Its totient is φ = 70117018960.

The previous prime is 77128720861. The next prime is 77128720871. The reversal of 77128720867 is 76802782177.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 77128720867 - 2²³ = 77120332259 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77128720861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3505850938 + ... + 3505850959.

It is an arithmetic number, because the mean of its divisors is an integer number (21035105694).

Almost surely, 2^77128720867 is an apocalyptic number.

77128720867 is a deficient number, since it is larger than the sum of its proper divisors (7011701909).

77128720867 is a wasteful number, since it uses less digits than its factorization.

77128720867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7011701908.

The product of its (nonzero) digits is 3687936, while the sum is 55.

The spelling of 77128720867 in words is "seventy-seven billion, one hundred twenty-eight million, seven hundred twenty thousand, eight hundred sixty-seven".