128685 has 16 divisors (see below), whose sum is σ = 215424. Its totient is φ = 65472.

The previous prime is 128683. The next prime is 128693. The reversal of 128685 is 586821.

It is not a de Polignac number, because 128685 - 2¹ = 128683 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 159 + ... + 531.

It is an arithmetic number, because the mean of its divisors is an integer number (13464).

2¹²⁸⁶⁸⁵ is an apocalyptic number.

128685 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

128685 is a deficient number, since it is larger than the sum of its proper divisors (86739).

128685 is a wasteful number, since it uses less digits than its factorization.

128685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 404.

The product of its digits is 3840, while the sum is 30.

The square root of 128685 is about 358.7269156336. The cubic root of 128685 is about 50.4865827179.

The spelling of 128685 in words is "one hundred twenty-eight thousand, six hundred eighty-five".