243315581 has 2 divisors, whose sum is σ = 243315582. Its totient is φ = 243315580.

The previous prime is 243315571. The next prime is 243315637. The reversal of 243315581 is 185513342.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 243204025 + 111556 = 15595^2 + 334^2 .

It is a cyclic number.

It is not a de Polignac number, because 243315581 - 2⁶ = 243315517 is a prime.

It is a super-2 number, since 2×243315581² = 118404943914735122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen 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 (243315571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121657790 + 121657791.

It is an arithmetic number, because the mean of its divisors is an integer number (121657791).

Almost surely, 2^243315581 is an apocalyptic number.

It is an amenable number.

243315581 is a deficient number, since it is larger than the sum of its proper divisors (1).

243315581 is an equidigital number, since it uses as much as digits as its factorization.

243315581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14400, while the sum is 32.

The square root of 243315581 is about 15598.5762491325. The cubic root of 243315581 is about 624.2951678908.

The spelling of 243315581 in words is "two hundred forty-three million, three hundred fifteen thousand, five hundred eighty-one".