128665791 has 12 divisors (see below), whose sum is σ = 185969160. Its totient is φ = 85722480.

The previous prime is 128665783. The next prime is 128665811. The reversal of 128665791 is 197566821.

128665791 is a `hidden beast` number, since 12 + 8 + 66 + 579 + 1 = 666.

It is not a de Polignac number, because 128665791 - 2³ = 128665783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128665751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14545 + ... + 21653.

It is an arithmetic number, because the mean of its divisors is an integer number (15497430).

Almost surely, 2^128665791 is an apocalyptic number.

128665791 is a deficient number, since it is larger than the sum of its proper divisors (57303369).

128665791 is a wasteful number, since it uses less digits than its factorization.

128665791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9126 (or 9123 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 128665791 is about 11343.0944190728. The cubic root of 128665791 is about 504.8407052396.

The spelling of 128665791 in words is "one hundred twenty-eight million, six hundred sixty-five thousand, seven hundred ninety-one".