128189521 has 2 divisors, whose sum is σ = 128189522. Its totient is φ = 128189520.

The previous prime is 128189519. The next prime is 128189627. The reversal of 128189521 is 125981821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 115799121 + 12390400 = 10761^2 + 3520^2 .

It is a cyclic number.

It is not a de Polignac number, because 128189521 - 2¹ = 128189519 is a prime.

Together with 128189519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (128189221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64094760 + 64094761.

It is an arithmetic number, because the mean of its divisors is an integer number (64094761).

Almost surely, 2^128189521 is an apocalyptic number.

It is an amenable number.

128189521 is a deficient number, since it is larger than the sum of its proper divisors (1).

128189521 is an equidigital number, since it uses as much as digits as its factorization.

128189521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 37.

The square root of 128189521 is about 11322.0811249522. The cubic root of 128189521 is about 504.2170280256.

The spelling of 128189521 in words is "one hundred twenty-eight million, one hundred eighty-nine thousand, five hundred twenty-one".