243311521 has 2 divisors, whose sum is σ = 243311522. Its totient is φ = 243311520.

The previous prime is 243311491. The next prime is 243311561. The reversal of 243311521 is 125113342.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 239166225 + 4145296 = 15465^2 + 2036^2 .

It is a cyclic number.

It is not a de Polignac number, because 243311521 - 2²⁷ = 109093793 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 243311492 and 243311501.

It is not a weakly prime, because it can be changed into another prime (243311561) 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, 121655760 + 121655761.

It is an arithmetic number, because the mean of its divisors is an integer number (121655761).

Almost surely, 2^243311521 is an apocalyptic number.

It is an amenable number.

243311521 is a deficient number, since it is larger than the sum of its proper divisors (1).

243311521 is an equidigital number, since it uses as much as digits as its factorization.

243311521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 720, while the sum is 22.

The square root of 243311521 is about 15598.4461085071. The cubic root of 243311521 is about 624.2916955108.

Adding to 243311521 its reverse (125113342), we get a palindrome (368424863).

It can be divided in two parts, 24331 and 1521, that added together give a palindrome (25852).

The spelling of 243311521 in words is "two hundred forty-three million, three hundred eleven thousand, five hundred twenty-one".