243687561 has 8 divisors (see below), whose sum is σ = 349910400. Its totient is φ = 149961552.

The previous prime is 243687491. The next prime is 243687589. The reversal of 243687561 is 165786342.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 243687561 - 2¹⁰ = 243686537 is a prime.

It is a super-2 number, since 2×243687561² = 118767254772257442, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (243687361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3124161 + ... + 3124238.

It is an arithmetic number, because the mean of its divisors is an integer number (43738800).

Almost surely, 2^243687561 is an apocalyptic number.

It is an amenable number.

243687561 is a deficient number, since it is larger than the sum of its proper divisors (106222839).

243687561 is a wasteful number, since it uses less digits than its factorization.

243687561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6248415.

The product of its digits is 241920, while the sum is 42.

The square root of 243687561 is about 15610.4952195630. The cubic root of 243687561 is about 624.6131459864.

The spelling of 243687561 in words is "two hundred forty-three million, six hundred eighty-seven thousand, five hundred sixty-one".