128623009 has 4 divisors (see below), whose sum is σ = 130803120. Its totient is φ = 126442900.

The previous prime is 128622979. The next prime is 128623013. The reversal of 128623009 is 900326821.

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 not a de Polignac number, because 128623009 - 2¹³ = 128614817 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128623609) 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 in 3 ways as a sum of consecutive naturals, for example, 1089967 + ... + 1090084.

It is an arithmetic number, because the mean of its divisors is an integer number (32700780).

Almost surely, 2^128623009 is an apocalyptic number.

It is an amenable number.

128623009 is a deficient number, since it is larger than the sum of its proper divisors (2180111).

128623009 is an equidigital number, since it uses as much as digits as its factorization.

128623009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2180110.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 128623009 is about 11341.2084453113. The cubic root of 128623009 is about 504.7847450419.

The spelling of 128623009 in words is "one hundred twenty-eight million, six hundred twenty-three thousand, nine".