128641 has 4 divisors (see below), whose sum is σ = 129492. Its totient is φ = 127792.

The previous prime is 128629. The next prime is 128657. The reversal of 128641 is 146821.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 146821 = 41 ⋅3581.

It can be written as a sum of positive squares in 2 ways, for example, as 87025 + 41616 = 295^2 + 204^2 .

It is a cyclic number.

It is not a de Polignac number, because 128641 - 2¹⁵ = 95873 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128621) 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, 130 + ... + 523.

It is an arithmetic number, because the mean of its divisors is an integer number (32373).

2¹²⁸⁶⁴¹ is an apocalyptic number.

It is an amenable number.

128641 is a deficient number, since it is larger than the sum of its proper divisors (851).

128641 is an equidigital number, since it uses as much as digits as its factorization.

128641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850.

The product of its digits is 384, while the sum is 22.

The square root of 128641 is about 358.6655824023. The cubic root of 128641 is about 50.4808279346.

The spelling of 128641 in words is "one hundred twenty-eight thousand, six hundred forty-one".