123809 has 8 divisors (see below), whose sum is σ = 147840. Its totient is φ = 101376.

The previous prime is 123803. The next prime is 123817. The reversal of 123809 is 908321.

123809 = T₂₂ + T₂₃ + ... + T₉₀.

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 123809 - 2⁸ = 123553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (123803) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 224 + ... + 545.

It is an arithmetic number, because the mean of its divisors is an integer number (18480).

2¹²³⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

123809 is a deficient number, since it is larger than the sum of its proper divisors (24031).

123809 is an equidigital number, since it uses as much as digits as its factorization.

123809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 799.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 123809 is about 351.8650309423. The cubic root of 123809 is about 49.8406929644.

The spelling of 123809 in words is "one hundred twenty-three thousand, eight hundred nine".