243311909 has 2 divisors, whose sum is σ = 243311910. Its totient is φ = 243311908.

The previous prime is 243311899. The next prime is 243311911. The reversal of 243311909 is 909113342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 241895809 + 1416100 = 15553^2 + 1190^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-243311909 is a prime.

It is a super-2 number, since 2×243311909² = 118401370122448562, which contains 22 as substring.

Together with 243311911, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243311609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121655954 + 121655955.

It is an arithmetic number, because the mean of its divisors is an integer number (121655955).

Almost surely, 2^243311909 is an apocalyptic number.

It is an amenable number.

243311909 is a deficient number, since it is larger than the sum of its proper divisors (1).

243311909 is an equidigital number, since it uses as much as digits as its factorization.

243311909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 243311909 is about 15598.4585456384. The cubic root of 243311909 is about 624.2920273557.

The spelling of 243311909 in words is "two hundred forty-three million, three hundred eleven thousand, nine hundred nine".