128861 has 2 divisors, whose sum is σ = 128862. Its totient is φ = 128860.

The previous prime is 128857. The next prime is 128873. The reversal of 128861 is 168821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 96100 + 32761 = 310^2 + 181^2 .

It is a cyclic number.

It is not a de Polignac number, because 128861 - 2² = 128857 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64430 + 64431.

It is an arithmetic number, because the mean of its divisors is an integer number (64431).

2¹²⁸⁸⁶¹ is an apocalyptic number.

It is an amenable number.

128861 is a deficient number, since it is larger than the sum of its proper divisors (1).

128861 is an equidigital number, since it uses as much as digits as its factorization.

128861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 768, while the sum is 26.

The square root of 128861 is about 358.9721437661. The cubic root of 128861 is about 50.5095887422.

It can be divided in two parts, 128 and 861, that added together give a palindrome (989).

The spelling of 128861 in words is "one hundred twenty-eight thousand, eight hundred sixty-one".