123209 has 2 divisors, whose sum is σ = 123210. Its totient is φ = 123208.

The previous prime is 123203. The next prime is 123217. The reversal of 123209 is 902321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 107584 + 15625 = 328^2 + 125^2 .

It is a cyclic number.

It is not a de Polignac number, because 123209 - 2⁸ = 122953 is a prime.

It is a plaindrome in base 15.

It is not a weakly prime, because it can be changed into another prime (123203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61604 + 61605.

It is an arithmetic number, because the mean of its divisors is an integer number (61605).

2¹²³²⁰⁹ is an apocalyptic number.

It is an amenable number.

123209 is a deficient number, since it is larger than the sum of its proper divisors (1).

123209 is an equidigital number, since it uses as much as digits as its factorization.

123209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 123209 is about 351.0113958264. The cubic root of 123209 is about 49.7600503251.

The spelling of 123209 in words is "one hundred twenty-three thousand, two hundred nine".