18868442561 has 4 divisors (see below), whose sum is σ = 18875451732. Its totient is φ = 18861433392.

The previous prime is 18868442533. The next prime is 18868442599. The reversal of 18868442561 is 16524486881.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9378760336 + 9489682225 = 96844^2 + 97415^2 .

It is a cyclic number.

It is not a de Polignac number, because 18868442561 - 2¹⁴ = 18868426177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18868441561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3500546 + ... + 3505931.

It is an arithmetic number, because the mean of its divisors is an integer number (4718862933).

Almost surely, 2^18868442561 is an apocalyptic number.

It is an amenable number.

18868442561 is a deficient number, since it is larger than the sum of its proper divisors (7009171).

18868442561 is an equidigital number, since it uses as much as digits as its factorization.

18868442561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7009170.

The product of its digits is 2949120, while the sum is 53.

The spelling of 18868442561 in words is "eighteen billion, eight hundred sixty-eight million, four hundred forty-two thousand, five hundred sixty-one".