243243557 has 2 divisors, whose sum is σ = 243243558. Its totient is φ = 243243556.

The previous prime is 243243523. The next prime is 243243569. The reversal of 243243557 is 755342342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 204318436 + 38925121 = 14294^2 + 6239^2 .

It is a cyclic number.

It is not a de Polignac number, because 243243557 - 2⁶ = 243243493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243245557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121621778 + 121621779.

It is an arithmetic number, because the mean of its divisors is an integer number (121621779).

Almost surely, 2^243243557 is an apocalyptic number.

It is an amenable number.

243243557 is a deficient number, since it is larger than the sum of its proper divisors (1).

243243557 is an equidigital number, since it uses as much as digits as its factorization.

243243557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100800, while the sum is 35.

The square root of 243243557 is about 15596.2674060174. The cubic root of 243243557 is about 624.2335624752.

Adding to 243243557 its reverse (755342342), we get a palindrome (998585899).

The spelling of 243243557 in words is "two hundred forty-three million, two hundred forty-three thousand, five hundred fifty-seven".