91000181 has 2 divisors, whose sum is σ = 91000182. Its totient is φ = 91000180.

The previous prime is 91000171. The next prime is 91000187. The reversal of 91000181 is 18100019.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63856081 + 27144100 = 7991^2 + 5210^2 .

It is a cyclic number.

It is not a de Polignac number, because 91000181 - 2¹⁰ = 90999157 is a prime.

It is a super-2 number, since 2×91000181² = 16562065884065522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91000187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45500090 + 45500091.

It is an arithmetic number, because the mean of its divisors is an integer number (45500091).

Almost surely, 2^91000181 is an apocalyptic number.

It is an amenable number.

91000181 is a deficient number, since it is larger than the sum of its proper divisors (1).

91000181 is an equidigital number, since it uses as much as digits as its factorization.

91000181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 20.

The square root of 91000181 is about 9539.4015011425. The cubic root of 91000181 is about 449.7944427425.

It can be divided in two parts, 9100018 and 1, that added together give a palindrome (9100019).

The spelling of 91000181 in words is "ninety-one million, one hundred eighty-one", and thus it is an aban number.