128805 has 16 divisors (see below), whose sum is σ = 213504. Its totient is φ = 66240.

The previous prime is 128767. The next prime is 128813. The reversal of 128805 is 508821.

It is not a de Polignac number, because 128805 - 2⁷ = 128677 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 327 + ... + 603.

It is an arithmetic number, because the mean of its divisors is an integer number (13344).

2¹²⁸⁸⁰⁵ is an apocalyptic number.

128805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

128805 is a deficient number, since it is larger than the sum of its proper divisors (84699).

128805 is a wasteful number, since it uses less digits than its factorization.

128805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316.

The product of its (nonzero) digits is 640, while the sum is 24.

The square root of 128805 is about 358.8941348086. The cubic root of 128805 is about 50.5022709171.

The spelling of 128805 in words is "one hundred twenty-eight thousand, eight hundred five".