243320511557 has 2 divisors, whose sum is σ = 243320511558. Its totient is φ = 243320511556.

The previous prime is 243320511493. The next prime is 243320511559. The reversal of 243320511557 is 755115023342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 150222907396 + 93097604161 = 387586^2 + 305119^2 .

It is a cyclic number.

It is not a de Polignac number, because 243320511557 - 2⁶ = 243320511493 is a prime.

Together with 243320511559, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 243320511557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243320511559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121660255778 + 121660255779.

It is an arithmetic number, because the mean of its divisors is an integer number (121660255779).

Almost surely, 2^243320511557 is an apocalyptic number.

It is an amenable number.

243320511557 is a deficient number, since it is larger than the sum of its proper divisors (1).

243320511557 is an equidigital number, since it uses as much as digits as its factorization.

243320511557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126000, while the sum is 38.

Adding to 243320511557 its reverse (755115023342), we get a palindrome (998435534899).

The spelling of 243320511557 in words is "two hundred forty-three billion, three hundred twenty million, five hundred eleven thousand, five hundred fifty-seven".