128809999 has 2 divisors, whose sum is σ = 128810000. Its totient is φ = 128809998.

The previous prime is 128809973. The next prime is 128810021. The reversal of 128809999 is 999908821.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 128809999 - 2⁹ = 128809487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128809199) 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, 64404999 + 64405000.

It is an arithmetic number, because the mean of its divisors is an integer number (64405000).

Almost surely, 2^128809999 is an apocalyptic number.

128809999 is a deficient number, since it is larger than the sum of its proper divisors (1).

128809999 is an equidigital number, since it uses as much as digits as its factorization.

128809999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 839808, while the sum is 55.

The square root of 128809999 is about 11349.4492817934. The cubic root of 128809999 is about 505.0292424984.

The spelling of 128809999 in words is "one hundred twenty-eight million, eight hundred nine thousand, nine hundred ninety-nine".