128641709 has 12 divisors (see below), whose sum is σ = 154806300. Its totient is φ = 106460928.

The previous prime is 128641693. The next prime is 128641717. The reversal of 128641709 is 907146821.

It can be written as a sum of positive squares in 2 ways, for example, as 103591684 + 25050025 = 10178^2 + 5005^2 .

It is not a de Polignac number, because 128641709 - 2⁴ = 128641693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128641739) 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, 43844 + ... + 46685.

It is an arithmetic number, because the mean of its divisors is an integer number (12900525).

Almost surely, 2^128641709 is an apocalyptic number.

It is an amenable number.

128641709 is a deficient number, since it is larger than the sum of its proper divisors (26164591).

128641709 is an equidigital number, since it uses as much as digits as its factorization.

128641709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90572 (or 90565 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 128641709 is about 11342.0328424846. The cubic root of 128641709 is about 504.8092067547.

The spelling of 128641709 in words is "one hundred twenty-eight million, six hundred forty-one thousand, seven hundred nine".