128621 has 2 divisors, whose sum is σ = 128622. Its totient is φ = 128620.

The previous prime is 128603. The next prime is 128629. The reversal of 128621 is 126821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 84100 + 44521 = 290^2 + 211^2 .

It is a cyclic number.

It is not a de Polignac number, because 128621 - 2¹⁰ = 127597 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 128593 and 128602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64310 + 64311.

It is an arithmetic number, because the mean of its divisors is an integer number (64311).

2¹²⁸⁶²¹ is an apocalyptic number.

It is an amenable number.

128621 is a deficient number, since it is larger than the sum of its proper divisors (1).

128621 is an equidigital number, since it uses as much as digits as its factorization.

128621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 192, while the sum is 20.

The square root of 128621 is about 358.6377001934. The cubic root of 128621 is about 50.4782116902.

The spelling of 128621 in words is "one hundred twenty-eight thousand, six hundred twenty-one".