78891191 has 2 divisors, whose sum is σ = 78891192. Its totient is φ = 78891190.

The previous prime is 78891181. The next prime is 78891193. The reversal of 78891191 is 19119887.

It is a strong prime.

It is an emirp because it is prime and its reverse (19119887) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78891191 - 2²⁶ = 11782327 is a prime.

Together with 78891193, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78891193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39445595 + 39445596.

It is an arithmetic number, because the mean of its divisors is an integer number (39445596).

Almost surely, 2^78891191 is an apocalyptic number.

78891191 is a deficient number, since it is larger than the sum of its proper divisors (1).

78891191 is an equidigital number, since it uses as much as digits as its factorization.

78891191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 44.

The square root of 78891191 is about 8882.0713237398. The cubic root of 78891191 is about 428.8869555422.

The spelling of 78891191 in words is "seventy-eight million, eight hundred ninety-one thousand, one hundred ninety-one".