91618537891 has 2 divisors, whose sum is σ = 91618537892. Its totient is φ = 91618537890.

The previous prime is 91618537889. The next prime is 91618537931. The reversal of 91618537891 is 19873581619.

It is a weak prime.

It is an emirp because it is prime and its reverse (19873581619) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91618537891 - 2¹ = 91618537889 is a prime.

Together with 91618537889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (91618537841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45809268945 + 45809268946.

It is an arithmetic number, because the mean of its divisors is an integer number (45809268946).

Almost surely, 2^91618537891 is an apocalyptic number.

91618537891 is a deficient number, since it is larger than the sum of its proper divisors (1).

91618537891 is an equidigital number, since it uses as much as digits as its factorization.

91618537891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3265920, while the sum is 58.

The spelling of 91618537891 in words is "ninety-one billion, six hundred eighteen million, five hundred thirty-seven thousand, eight hundred ninety-one".