128123609 has 2 divisors, whose sum is σ = 128123610. Its totient is φ = 128123608.

The previous prime is 128123587. The next prime is 128123621. The reversal of 128123609 is 906321821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 125328025 + 2795584 = 11195^2 + 1672^2 .

It is a cyclic number.

It is not a de Polignac number, because 128123609 - 2⁸ = 128123353 is a prime.

It is not a weakly prime, because it can be changed into another prime (128123659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64061804 + 64061805.

It is an arithmetic number, because the mean of its divisors is an integer number (64061805).

Almost surely, 2^128123609 is an apocalyptic number.

It is an amenable number.

128123609 is a deficient number, since it is larger than the sum of its proper divisors (1).

128123609 is an equidigital number, since it uses as much as digits as its factorization.

128123609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 128123609 is about 11319.1699784039. The cubic root of 128123609 is about 504.1305944124.

The spelling of 128123609 in words is "one hundred twenty-eight million, one hundred twenty-three thousand, six hundred nine".