128939 has 2 divisors, whose sum is σ = 128940. Its totient is φ = 128938.

The previous prime is 128923. The next prime is 128941. The reversal of 128939 is 939821.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 128939 - 2⁴ = 128923 is a prime.

It is a Sophie Germain prime.

Together with 128941, it forms a pair of twin primes.

It is a Chen prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (128959) 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, 64469 + 64470.

It is an arithmetic number, because the mean of its divisors is an integer number (64470).

2¹²⁸⁹³⁹ is an apocalyptic number.

128939 is a deficient number, since it is larger than the sum of its proper divisors (1).

128939 is an equidigital number, since it uses as much as digits as its factorization.

128939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 32.

The square root of 128939 is about 359.0807708580. The cubic root of 128939 is about 50.5197778951.

The spelling of 128939 in words is "one hundred twenty-eight thousand, nine hundred thirty-nine".