1986638366891 has 4 divisors (see below), whose sum is σ = 1986653394072. Its totient is φ = 1986623339712.

The previous prime is 1986638366873. The next prime is 1986638366897.

1986638366891 is nontrivially palindromic in base 10.

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

It is a cyclic number.

It is not a de Polignac number, because 1986638366891 - 2³⁴ = 1969458497707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1986638366897) 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, 7313510 + ... + 7580283.

It is an arithmetic number, because the mean of its divisors is an integer number (496663348518).

Almost surely, 2^{1986638366891} is an apocalyptic number.

1986638366891 is a deficient number, since it is larger than the sum of its proper divisors (15027181).

1986638366891 is a wasteful number, since it uses less digits than its factorization.

1986638366891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15027180.

The product of its digits is 483729408, while the sum is 74.

The spelling of 1986638366891 in words is "one trillion, nine hundred eighty-six billion, six hundred thirty-eight million, three hundred sixty-six thousand, eight hundred ninety-one".