18891566866 has 8 divisors (see below), whose sum is σ = 28337998140. Its totient is φ = 9445567488.

The previous prime is 18891566849. The next prime is 18891566887. The reversal of 18891566866 is 66866519881.

It can be written as a sum of positive squares in 2 ways, for example, as 18778591225 + 112975641 = 137035^2 + 10629^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 18891566798 and 18891566807.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44370 + ... + 199378.

Almost surely, 2^18891566866 is an apocalyptic number.

18891566866 is a deficient number, since it is larger than the sum of its proper divisors (9446431274).

18891566866 is a wasteful number, since it uses less digits than its factorization.

18891566866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215948.

The product of its digits is 29859840, while the sum is 64.

The spelling of 18891566866 in words is "eighteen billion, eight hundred ninety-one million, five hundred sixty-six thousand, eight hundred sixty-six".