243213121 has 2 divisors, whose sum is σ = 243213122. Its totient is φ = 243213120.

The previous prime is 243213119. The next prime is 243213143. The reversal of 243213121 is 121312342.

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., 231040000 + 12173121 = 15200^2 + 3489^2 .

It is a cyclic number.

It is not a de Polignac number, because 243213121 - 2¹ = 243213119 is a prime.

Together with 243213119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (243213181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121606560 + 121606561.

It is an arithmetic number, because the mean of its divisors is an integer number (121606561).

Almost surely, 2^243213121 is an apocalyptic number.

It is an amenable number.

243213121 is a deficient number, since it is larger than the sum of its proper divisors (1).

243213121 is an equidigital number, since it uses as much as digits as its factorization.

243213121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 19.

The square root of 243213121 is about 15595.2916292066. The cubic root of 243213121 is about 624.2075255194.

Adding to 243213121 its reverse (121312342), we get a palindrome (364525463).

The spelling of 243213121 in words is "two hundred forty-three million, two hundred thirteen thousand, one hundred twenty-one".