91856187289 has 2 divisors, whose sum is σ = 91856187290. Its totient is φ = 91856187288.

The previous prime is 91856187217. The next prime is 91856187299. The reversal of 91856187289 is 98278165819.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 85720128400 + 6136058889 = 292780^2 + 78333^2 .

It is an emirp because it is prime and its reverse (98278165819) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91856187289 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91856187289.

It is not a weakly prime, because it can be changed into another prime (91856187299) 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 as a sum of consecutive naturals, namely, 45928093644 + 45928093645.

It is an arithmetic number, because the mean of its divisors is an integer number (45928093645).

Almost surely, 2^91856187289 is an apocalyptic number.

It is an amenable number.

91856187289 is a deficient number, since it is larger than the sum of its proper divisors (1).

91856187289 is an equidigital number, since it uses as much as digits as its factorization.

91856187289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17418240, while the sum is 64.

The spelling of 91856187289 in words is "ninety-one billion, eight hundred fifty-six million, one hundred eighty-seven thousand, two hundred eighty-nine".