91681181 has 2 divisors, whose sum is σ = 91681182. Its totient is φ = 91681180.

The previous prime is 91681171. The next prime is 91681193. The reversal of 91681181 is 18118619.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55741156 + 35940025 = 7466^2 + 5995^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91681181 is a prime.

It is a super-2 number, since 2×91681181² = 16810877899109522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91681111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45840590 + 45840591.

It is an arithmetic number, because the mean of its divisors is an integer number (45840591).

Almost surely, 2^91681181 is an apocalyptic number.

It is an amenable number.

91681181 is a deficient number, since it is larger than the sum of its proper divisors (1).

91681181 is an equidigital number, since it uses as much as digits as its factorization.

91681181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 35.

The square root of 91681181 is about 9575.0290338985. The cubic root of 91681181 is about 450.9136679374.

The spelling of 91681181 in words is "ninety-one million, six hundred eighty-one thousand, one hundred eighty-one".