128990809 has 2 divisors, whose sum is σ = 128990810. Its totient is φ = 128990808.

The previous prime is 128990777. The next prime is 128990821. The reversal of 128990809 is 908099821.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 100400400 + 28590409 = 10020^2 + 5347^2 .

It is an emirp because it is prime and its reverse (908099821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128990809 - 2⁵ = 128990777 is a prime.

It is not a weakly prime, because it can be changed into another prime (128990839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64495404 + 64495405.

It is an arithmetic number, because the mean of its divisors is an integer number (64495405).

Almost surely, 2^128990809 is an apocalyptic number.

It is an amenable number.

128990809 is a deficient number, since it is larger than the sum of its proper divisors (1).

128990809 is an equidigital number, since it uses as much as digits as its factorization.

128990809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 46.

The square root of 128990809 is about 11357.4120731793. The cubic root of 128990809 is about 505.2654344232.

The spelling of 128990809 in words is "one hundred twenty-eight million, nine hundred ninety thousand, eight hundred nine".