2309 has 2 divisors, whose sum is σ = 2310.
Its totient is φ = 2308.
The previous prime is 2297. The next prime is 2311. The reversal of 2309 is 9032.
It is a happy number.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 2209 + 100 = 47^2 + 10^2
It is a cyclic number.
It is not a de Polignac number, because 2309 - 24 = 2293 is a prime.
Together with 2311, it forms a pair of twin primes.
It is a Chen prime.
It is an alternating number because its digits alternate between even and odd.
It is a junction number, because it is equal to n+sod(n) for n = 2293 and 2302.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (2339) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1154 + 1155.
It is an arithmetic number, because the mean of its divisors is an integer number (1155).
It is an amenable number.
2309 is a deficient number, since it is larger than the sum of its proper divisors (1).
2309 is an equidigital number, since it uses as much as digits as its factorization.
2309 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 54, while the sum is 14.
The square root of 2309 is about 48.0520551069.
The cubic root of 2309 is about 13.2172562802.
The spelling of 2309 in words is "two thousand, three hundred nine".