243989761 has 2 divisors, whose sum is σ = 243989762. Its totient is φ = 243989760.

The previous prime is 243989749. The next prime is 243989777. The reversal of 243989761 is 167989342.

243989761 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 170459136 + 73530625 = 13056^2 + 8575^2 .

It is a cyclic number.

It is not a de Polignac number, because 243989761 - 2¹⁹ = 243465473 is a prime.

It is not a weakly prime, because it can be changed into another prime (243989741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121994880 + 121994881.

It is an arithmetic number, because the mean of its divisors is an integer number (121994881).

Almost surely, 2^243989761 is an apocalyptic number.

It is an amenable number.

243989761 is a deficient number, since it is larger than the sum of its proper divisors (1).

243989761 is an equidigital number, since it uses as much as digits as its factorization.

243989761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 653184, while the sum is 49.

The square root of 243989761 is about 15620.1716059716. The cubic root of 243989761 is about 624.8712361936.

The spelling of 243989761 in words is "two hundred forty-three million, nine hundred eighty-nine thousand, seven hundred sixty-one".