129009 has 4 divisors (see below), whose sum is σ = 172016. Its totient is φ = 86004.

The previous prime is 129001. The next prime is 129011. The reversal of 129009 is 900921.

129009 = 76² + 77² + ... + 93².

It is a happy number.

129009 is nontrivially palindromic in base 16.

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 129009 - 2³ = 129001 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

129009 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (129001) 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, 21499 + ... + 21504.

It is an arithmetic number, because the mean of its divisors is an integer number (43004).

2¹²⁹⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

129009 is a deficient number, since it is larger than the sum of its proper divisors (43007).

129009 is an equidigital number, since it uses as much as digits as its factorization.

129009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43006.

The product of its (nonzero) digits is 162, while the sum is 21.

The square root of 129009 is about 359.1782287389. The cubic root of 129009 is about 50.5289185086.

The spelling of 129009 in words is "one hundred twenty-nine thousand, nine".