1986666891 has 16 divisors (see below), whose sum is σ = 2891388288. Its totient is φ = 1203336000.

The previous prime is 1986666839. The next prime is 1986666901.

1986666891 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1986666891 - 2¹⁰ = 1986665867 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1986661891) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42720 + ... + 76146.

It is an arithmetic number, because the mean of its divisors is an integer number (180711768).

Almost surely, 2^1986666891 is an apocalyptic number.

1986666891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1986666891 is a deficient number, since it is larger than the sum of its proper divisors (904721397).

1986666891 is a wasteful number, since it uses less digits than its factorization.

1986666891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35242.

The product of its digits is 6718464, while the sum is 60.

The square root of 1986666891 is about 44572.0415843834. The cubic root of 1986666891 is about 1257.1150276780.

The spelling of 1986666891 in words is "one billion, nine hundred eighty-six million, six hundred sixty-six thousand, eight hundred ninety-one".