243243521 has 2 divisors, whose sum is σ = 243243522. Its totient is φ = 243243520.

The previous prime is 243243509. The next prime is 243243523. The reversal of 243243521 is 125342342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 226954225 + 16289296 = 15065^2 + 4036^2 .

It is a cyclic number.

It is not a de Polignac number, because 243243521 - 2¹⁸ = 242981377 is a prime.

Together with 243243523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (243243523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121621760 + 121621761.

It is an arithmetic number, because the mean of its divisors is an integer number (121621761).

Almost surely, 2^243243521 is an apocalyptic number.

It is an amenable number.

243243521 is a deficient number, since it is larger than the sum of its proper divisors (1).

243243521 is an equidigital number, since it uses as much as digits as its factorization.

243243521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 26.

The square root of 243243521 is about 15596.2662518950. The cubic root of 243243521 is about 624.2335316797.

Adding to 243243521 its reverse (125342342), we get a palindrome (368585863).

The spelling of 243243521 in words is "two hundred forty-three million, two hundred forty-three thousand, five hundred twenty-one".