128709 has 20 divisors (see below), whose sum is σ = 220704. Its totient is φ = 73224.

The previous prime is 128693. The next prime is 128717. The reversal of 128709 is 907821.

It is not a de Polignac number, because 128709 - 2⁴ = 128693 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 454 + ... + 680.

2¹²⁸⁷⁰⁹ is an apocalyptic number.

It is an amenable number.

128709 is a deficient number, since it is larger than the sum of its proper divisors (91995).

128709 is an equidigital number, since it uses as much as digits as its factorization.

128709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246 (or 237 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 128709 is about 358.7603657039. The cubic root of 128709 is about 50.4897211377.

The spelling of 128709 in words is "one hundred twenty-eight thousand, seven hundred nine".