128667689 has 2 divisors, whose sum is σ = 128667690. Its totient is φ = 128667688.

The previous prime is 128667661. The next prime is 128667709. The reversal of 128667689 is 986766821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 98505625 + 30162064 = 9925^2 + 5492^2 .

It is a cyclic number.

It is not a de Polignac number, because 128667689 - 2¹² = 128663593 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128667689.

It is not a weakly prime, because it can be changed into another prime (128657689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64333844 + 64333845.

It is an arithmetic number, because the mean of its divisors is an integer number (64333845).

Almost surely, 2^128667689 is an apocalyptic number.

It is an amenable number.

128667689 is a deficient number, since it is larger than the sum of its proper divisors (1).

128667689 is an equidigital number, since it uses as much as digits as its factorization.

128667689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1741824, while the sum is 53.

The square root of 128667689 is about 11343.1780820015. The cubic root of 128667689 is about 504.8431875957.

The spelling of 128667689 in words is "one hundred twenty-eight million, six hundred sixty-seven thousand, six hundred eighty-nine".