191256863391 has 16 divisors (see below), whose sum is σ = 309102001920. Its totient is φ = 115913250360.

The previous prime is 191256863389. The next prime is 191256863401. The reversal of 191256863391 is 193368652191.

191256863391 is a `hidden beast` number, since 1 + 9 + 12 + 568 + 63 + 3 + 9 + 1 = 666.

191256863391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 191256863391 - 2¹ = 191256863389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191256863341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 321980955 + ... + 321981548.

It is an arithmetic number, because the mean of its divisors is an integer number (19318875120).

Almost surely, 2^191256863391 is an apocalyptic number.

191256863391 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

191256863391 is a deficient number, since it is larger than the sum of its proper divisors (117845138529).

191256863391 is a wasteful number, since it uses less digits than its factorization.

191256863391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643962523 (or 643962517 counting only the distinct ones).

The product of its digits is 2099520, while the sum is 54.

The spelling of 191256863391 in words is "one hundred ninety-one billion, two hundred fifty-six million, eight hundred sixty-three thousand, three hundred ninety-one".