128840521 has 2 divisors, whose sum is σ = 128840522. Its totient is φ = 128840520.

The previous prime is 128840473. The next prime is 128840563. The reversal of 128840521 is 125048821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78074896 + 50765625 = 8836^2 + 7125^2 .

It is a cyclic number.

It is not a de Polignac number, because 128840521 - 2¹⁵ = 128807753 is a prime.

It is not a weakly prime, because it can be changed into another prime (128840581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64420260 + 64420261.

It is an arithmetic number, because the mean of its divisors is an integer number (64420261).

Almost surely, 2^128840521 is an apocalyptic number.

It is an amenable number.

128840521 is a deficient number, since it is larger than the sum of its proper divisors (1).

128840521 is an equidigital number, since it uses as much as digits as its factorization.

128840521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5120, while the sum is 31.

The square root of 128840521 is about 11350.7938488900. The cubic root of 128840521 is about 505.0691288564.

The spelling of 128840521 in words is "one hundred twenty-eight million, eight hundred forty thousand, five hundred twenty-one".