243221075621 has 2 divisors, whose sum is σ = 243221075622. Its totient is φ = 243221075620.

The previous prime is 243221075599. The next prime is 243221075623. The reversal of 243221075621 is 126570122342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 230482567396 + 12738508225 = 480086^2 + 112865^2 .

It is a cyclic number.

It is not a de Polignac number, because 243221075621 - 2¹⁰ = 243221074597 is a prime.

Together with 243221075623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243221075623) 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, 121610537810 + 121610537811.

It is an arithmetic number, because the mean of its divisors is an integer number (121610537811).

Almost surely, 2^243221075621 is an apocalyptic number.

It is an amenable number.

243221075621 is a deficient number, since it is larger than the sum of its proper divisors (1).

243221075621 is an equidigital number, since it uses as much as digits as its factorization.

243221075621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 35.

Adding to 243221075621 its reverse (126570122342), we get a palindrome (369791197963).

The spelling of 243221075621 in words is "two hundred forty-three billion, two hundred twenty-one million, seventy-five thousand, six hundred twenty-one".