2191971191 has 4 divisors (see below), whose sum is σ = 2233329192. Its totient is φ = 2150613192.

The previous prime is 2191971163. The next prime is 2191971193. The reversal of 2191971191 is 1911791912.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2191971191 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 (2191971193) 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 3 ways as a sum of consecutive naturals, for example, 20678921 + ... + 20679026.

It is an arithmetic number, because the mean of its divisors is an integer number (558332298).

Almost surely, 2^2191971191 is an apocalyptic number.

2191971191 is a deficient number, since it is larger than the sum of its proper divisors (41358001).

2191971191 is an equidigital number, since it uses as much as digits as its factorization.

2191971191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41358000.

The product of its digits is 10206, while the sum is 41.

The square root of 2191971191 is about 46818.4919769956. The cubic root of 2191971191 is about 1299.0073667114.

The spelling of 2191971191 in words is "two billion, one hundred ninety-one million, nine hundred seventy-one thousand, one hundred ninety-one".