81235181 has 2 divisors, whose sum is σ = 81235182. Its totient is φ = 81235180.

The previous prime is 81235151. The next prime is 81235199. The reversal of 81235181 is 18153218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62173225 + 19061956 = 7885^2 + 4366^2 .

It is a cyclic number.

It is not a de Polignac number, because 81235181 - 2¹⁰ = 81234157 is a prime.

It is a super-2 number, since 2×81235181² = 13198309264205522, 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 (81235111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40617590 + 40617591.

It is an arithmetic number, because the mean of its divisors is an integer number (40617591).

Almost surely, 2^81235181 is an apocalyptic number.

It is an amenable number.

81235181 is a deficient number, since it is larger than the sum of its proper divisors (1).

81235181 is an equidigital number, since it uses as much as digits as its factorization.

81235181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1920, while the sum is 29.

The square root of 81235181 is about 9013.0561409546. The cubic root of 81235181 is about 433.0932191775.

Adding to 81235181 its reverse (18153218), we get a palindrome (99388399).

The spelling of 81235181 in words is "eighty-one million, two hundred thirty-five thousand, one hundred eighty-one".