91166787181 has 2 divisors, whose sum is σ = 91166787182. Its totient is φ = 91166787180.

The previous prime is 91166787149. The next prime is 91166787199. The reversal of 91166787181 is 18178766119.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70485471081 + 20681316100 = 265491^2 + 143810^2 .

It is a cyclic number.

It is not a de Polignac number, because 91166787181 - 2⁵ = 91166787149 is a prime.

It is a super-2 number, since 2×91166787181² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91166787121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45583393590 + 45583393591.

It is an arithmetic number, because the mean of its divisors is an integer number (45583393591).

Almost surely, 2^91166787181 is an apocalyptic number.

It is an amenable number.

91166787181 is a deficient number, since it is larger than the sum of its proper divisors (1).

91166787181 is an equidigital number, since it uses as much as digits as its factorization.

91166787181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1016064, while the sum is 55.

The spelling of 91166787181 in words is "ninety-one billion, one hundred sixty-six million, seven hundred eighty-seven thousand, one hundred eighty-one".