2191378187 has 2 divisors, whose sum is σ = 2191378188. Its totient is φ = 2191378186.

The previous prime is 2191378171. The next prime is 2191378193. The reversal of 2191378187 is 7818731912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2191378187 - 2⁴ = 2191378171 is a prime.

It is not a weakly prime, because it can be changed into another prime (2191371187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1095689093 + 1095689094.

It is an arithmetic number, because the mean of its divisors is an integer number (1095689094).

Almost surely, 2^2191378187 is an apocalyptic number.

2191378187 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191378187 is an equidigital number, since it uses as much as digits as its factorization.

2191378187 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 47.

The square root of 2191378187 is about 46812.1585381405. The cubic root of 2191378187 is about 1298.8902140098.

The spelling of 2191378187 in words is "two billion, one hundred ninety-one million, three hundred seventy-eight thousand, one hundred eighty-seven".