128012809 has 8 divisors (see below), whose sum is σ = 129773952. Its totient is φ = 126257040.

The previous prime is 128012803. The next prime is 128012821. The reversal of 128012809 is 908210821.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 128012809 - 2⁵ = 128012777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128012803) 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 7 ways as a sum of consecutive naturals, for example, 74767 + ... + 76459.

It is an arithmetic number, because the mean of its divisors is an integer number (16221744).

Almost surely, 2^128012809 is an apocalyptic number.

It is an amenable number.

128012809 is a deficient number, since it is larger than the sum of its proper divisors (1761143).

128012809 is an equidigital number, since it uses as much as digits as its factorization.

128012809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2687.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 128012809 is about 11314.2745679960. The cubic root of 128012809 is about 503.9852301563.

It can be divided in two parts, 128012 and 809, that added together give a palindrome (128821).

The spelling of 128012809 in words is "one hundred twenty-eight million, twelve thousand, eight hundred nine".