243115261 has 2 divisors, whose sum is σ = 243115262. Its totient is φ = 243115260.

The previous prime is 243115259. The next prime is 243115273. The reversal of 243115261 is 162511342.

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., 225180036 + 17935225 = 15006^2 + 4235^2 .

It is a cyclic number.

It is not a de Polignac number, because 243115261 - 2¹ = 243115259 is a prime.

Together with 243115259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243115661) 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, 121557630 + 121557631.

It is an arithmetic number, because the mean of its divisors is an integer number (121557631).

Almost surely, 2^243115261 is an apocalyptic number.

It is an amenable number.

243115261 is a deficient number, since it is larger than the sum of its proper divisors (1).

243115261 is an equidigital number, since it uses as much as digits as its factorization.

243115261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1440, while the sum is 25.

The square root of 243115261 is about 15592.1538281278. The cubic root of 243115261 is about 624.1237949175.

The spelling of 243115261 in words is "two hundred forty-three million, one hundred fifteen thousand, two hundred sixty-one".