128405 has 8 divisors (see below), whose sum is σ = 156984. Its totient is φ = 100800.

The previous prime is 128399. The next prime is 128411. The reversal of 128405 is 504821.

It is an interprime number because it is at equal distance from previous prime (128399) and next prime (128411).

It can be written as a sum of positive squares in 4 ways, for example, as 14161 + 114244 = 119^2 + 338^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 128405 - 2⁴ = 128389 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 11.

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 7 ways as a sum of consecutive naturals, for example, 95 + ... + 515.

It is an arithmetic number, because the mean of its divisors is an integer number (19623).

2¹²⁸⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

128405 is a deficient number, since it is larger than the sum of its proper divisors (28579).

128405 is an equidigital number, since it uses as much as digits as its factorization.

128405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 128405 is about 358.3364340951. The cubic root of 128405 is about 50.4499389537.

The spelling of 128405 in words is "one hundred twenty-eight thousand, four hundred five".