128021 has 2 divisors, whose sum is σ = 128022. Its totient is φ = 128020.

The previous prime is 127997. The next prime is 128033. The reversal of 128021 is 120821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81796 + 46225 = 286^2 + 215^2 .

It is a cyclic number.

It is not a de Polignac number, because 128021 - 2¹⁴ = 111637 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 127987 and 128005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64010 + 64011.

It is an arithmetic number, because the mean of its divisors is an integer number (64011).

2¹²⁸⁰²¹ is an apocalyptic number.

It is an amenable number.

128021 is a deficient number, since it is larger than the sum of its proper divisors (1).

128021 is an equidigital number, since it uses as much as digits as its factorization.

128021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 128021 is about 357.8002235885. The cubic root of 128021 is about 50.3995979224.

Adding to 128021 its reverse (120821), we get a palindrome (248842).

The spelling of 128021 in words is "one hundred twenty-eight thousand, twenty-one".