18666851687 has 4 divisors (see below), whose sum is σ = 20363838216. Its totient is φ = 16969865160.

The previous prime is 18666851657. The next prime is 18666851741. The reversal of 18666851687 is 78615866681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78615866681 = 11 ⋅7146896971.

It is a cyclic number.

It is not a de Polignac number, because 18666851687 - 2¹⁴ = 18666835303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18666851617) 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, 848493248 + ... + 848493269.

It is an arithmetic number, because the mean of its divisors is an integer number (5090959554).

Almost surely, 2^18666851687 is an apocalyptic number.

18666851687 is a deficient number, since it is larger than the sum of its proper divisors (1696986529).

18666851687 is a wasteful number, since it uses less digits than its factorization.

18666851687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1696986528.

The product of its digits is 23224320, while the sum is 62.

The spelling of 18666851687 in words is "eighteen billion, six hundred sixty-six million, eight hundred fifty-one thousand, six hundred eighty-seven".