128990209 has 4 divisors (see below), whose sum is σ = 130915504. Its totient is φ = 127064916.

The previous prime is 128990207. The next prime is 128990219. The reversal of 128990209 is 902099821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 128990209 - 2¹ = 128990207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128990207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 962547 + ... + 962680.

It is an arithmetic number, because the mean of its divisors is an integer number (32728876).

Almost surely, 2^128990209 is an apocalyptic number.

It is an amenable number.

128990209 is a deficient number, since it is larger than the sum of its proper divisors (1925295).

128990209 is an equidigital number, since it uses as much as digits as its factorization.

128990209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1925294.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 128990209 is about 11357.3856586804. The cubic root of 128990209 is about 505.2646510089.

The spelling of 128990209 in words is "one hundred twenty-eight million, nine hundred ninety thousand, two hundred nine".