128221 has 2 divisors, whose sum is σ = 128222. Its totient is φ = 128220.

The previous prime is 128213. The next prime is 128237. The reversal of 128221 is 122821.

It is an a-pointer prime, because the next prime (128237) can be obtained adding 128221 to its sum of digits (16).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 108900 + 19321 = 330^2 + 139^2 .

It is a cyclic number.

It is not a de Polignac number, because 128221 - 2³ = 128213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 128195 and 128204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64110 + 64111.

It is an arithmetic number, because the mean of its divisors is an integer number (64111).

2¹²⁸²²¹ is an apocalyptic number.

It is an amenable number.

128221 is a deficient number, since it is larger than the sum of its proper divisors (1).

128221 is an equidigital number, since it uses as much as digits as its factorization.

128221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64, while the sum is 16.

The square root of 128221 is about 358.0796000891. The cubic root of 128221 is about 50.4258297516.

The spelling of 128221 in words is "one hundred twenty-eight thousand, two hundred twenty-one".