128965 has 4 divisors (see below), whose sum is σ = 154764. Its totient is φ = 103168.

The previous prime is 128959. The next prime is 128969. The reversal of 128965 is 569821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 25281 + 103684 = 159^2 + 322^2 .

It is a cyclic number.

It is not a de Polignac number, because 128965 - 2⁷ = 128837 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128969) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12892 + ... + 12901.

It is an arithmetic number, because the mean of its divisors is an integer number (38691).

2¹²⁸⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

128965 is a deficient number, since it is larger than the sum of its proper divisors (25799).

128965 is an equidigital number, since it uses as much as digits as its factorization.

128965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25798.

The product of its digits is 4320, while the sum is 31.

The square root of 128965 is about 359.1169725869. The cubic root of 128965 is about 50.5231733662.

The spelling of 128965 in words is "one hundred twenty-eight thousand, nine hundred sixty-five".