2166208891 has 8 divisors (see below), whose sum is σ = 2700728064. Its totient is φ = 1687954920.

The previous prime is 2166208873. The next prime is 2166208907. The reversal of 2166208891 is 1988026612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 2166208891 - 2⁵ = 2166208859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2166208831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14066215 + ... + 14066368.

It is an arithmetic number, because the mean of its divisors is an integer number (337591008).

Almost surely, 2^2166208891 is an apocalyptic number.

2166208891 is a deficient number, since it is larger than the sum of its proper divisors (534519173).

2166208891 is a wasteful number, since it uses less digits than its factorization.

2166208891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28132601.

The product of its (nonzero) digits is 82944, while the sum is 43.

The square root of 2166208891 is about 46542.5492533445. The cubic root of 2166208891 is about 1293.8982078696.

The spelling of 2166208891 in words is "two billion, one hundred sixty-six million, two hundred eight thousand, eight hundred ninety-one".