128006689 has 2 divisors, whose sum is σ = 128006690. Its totient is φ = 128006688.

The previous prime is 128006687. The next prime is 128006699. The reversal of 128006689 is 986600821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 104387089 + 23619600 = 10217^2 + 4860^2 .

It is a cyclic number.

It is not a de Polignac number, because 128006689 - 2¹ = 128006687 is a prime.

Together with 128006687, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (128006687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64003344 + 64003345.

It is an arithmetic number, because the mean of its divisors is an integer number (64003345).

Almost surely, 2^128006689 is an apocalyptic number.

It is an amenable number.

128006689 is a deficient number, since it is larger than the sum of its proper divisors (1).

128006689 is an equidigital number, since it uses as much as digits as its factorization.

128006689 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 128006689 is about 11314.0041099515. The cubic root of 128006689 is about 503.9771985674.

The spelling of 128006689 in words is "one hundred twenty-eight million, six thousand, six hundred eighty-nine".