243121522421 has 2 divisors, whose sum is σ = 243121522422. Its totient is φ = 243121522420.

The previous prime is 243121522373. The next prime is 243121522433. The reversal of 243121522421 is 124225121342.

243121522421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 201613572196 + 41507950225 = 449014^2 + 203735^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-243121522421 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243121522481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121560761210 + 121560761211.

It is an arithmetic number, because the mean of its divisors is an integer number (121560761211).

Almost surely, 2^243121522421 is an apocalyptic number.

It is an amenable number.

243121522421 is a deficient number, since it is larger than the sum of its proper divisors (1).

243121522421 is an equidigital number, since it uses as much as digits as its factorization.

243121522421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7680, while the sum is 29.

Adding to 243121522421 its reverse (124225121342), we get a palindrome (367346643763).

The spelling of 243121522421 in words is "two hundred forty-three billion, one hundred twenty-one million, five hundred twenty-two thousand, four hundred twenty-one".