81181 has 2 divisors, whose sum is σ = 81182. Its totient is φ = 81180.

The previous prime is 81173. The next prime is 81197. The reversal of 81181 is 18118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72900 + 8281 = 270^2 + 91^2 .

It is a cyclic number.

It is not a de Polignac number, because 81181 - 2³ = 81173 is a prime.

It is a super-2 number, since 2×81181² = 13180709522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40590 + 40591.

It is an arithmetic number, because the mean of its divisors is an integer number (40591).

2⁸¹¹⁸¹ is an apocalyptic number.

81181 is the 165-th hex number.

It is an amenable number.

81181 is a deficient number, since it is larger than the sum of its proper divisors (1).

81181 is an equidigital number, since it uses as much as digits as its factorization.

81181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64, while the sum is 19.

The square root of 81181 is about 284.9227965608. The cubic root of 81181 is about 43.2996911797.

Adding to 81181 its reverse (18118), we get a palindrome (99299).

It can be divided in two parts, 81 and 181, that added together give a palindrome (262).

The spelling of 81181 in words is "eighty-one thousand, one hundred eighty-one".