243315516421 has 2 divisors, whose sum is σ = 243315516422. Its totient is φ = 243315516420.

The previous prime is 243315516403. The next prime is 243315516439. The reversal of 243315516421 is 124615513342.

It is a balanced prime because it is at equal distance from previous prime (243315516403) and next prime (243315516439).

It can be written as a sum of positive squares in only one way, i.e., 179665776900 + 63649739521 = 423870^2 + 252289^2 .

It is a cyclic number.

It is not a de Polignac number, because 243315516421 - 2¹⁹ = 243314992133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243315513421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121657758210 + 121657758211.

It is an arithmetic number, because the mean of its divisors is an integer number (121657758211).

Almost surely, 2^243315516421 is an apocalyptic number.

It is an amenable number.

243315516421 is a deficient number, since it is larger than the sum of its proper divisors (1).

243315516421 is an equidigital number, since it uses as much as digits as its factorization.

243315516421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 86400, while the sum is 37.

The spelling of 243315516421 in words is "two hundred forty-three billion, three hundred fifteen million, five hundred sixteen thousand, four hundred twenty-one".