129123509 has 4 divisors (see below), whose sum is σ = 129418080. Its totient is φ = 128828940.

The previous prime is 129123479. The next prime is 129123521. The reversal of 129123509 is 905321921.

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 129123509 - 2²⁴ = 112346293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129123569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 146627 + ... + 147504.

It is an arithmetic number, because the mean of its divisors is an integer number (32354520).

Almost surely, 2^129123509 is an apocalyptic number.

It is an amenable number.

129123509 is a deficient number, since it is larger than the sum of its proper divisors (294571).

129123509 is an equidigital number, since it uses as much as digits as its factorization.

129123509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294570.

The product of its (nonzero) digits is 4860, while the sum is 32.

The square root of 129123509 is about 11363.2525713371. The cubic root of 129123509 is about 505.4386399008.

The spelling of 129123509 in words is "one hundred twenty-nine million, one hundred twenty-three thousand, five hundred nine".