81100181 has 2 divisors, whose sum is σ = 81100182. Its totient is φ = 81100180.

The previous prime is 81100163. The next prime is 81100207. The reversal of 81100181 is 18100118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66161956 + 14938225 = 8134^2 + 3865^2 .

It is a cyclic number.

It is not a de Polignac number, because 81100181 - 2¹⁰ = 81099157 is a prime.

It is a super-2 number, since 2×81100181² = 13154478716465522, 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 (81100141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40550090 + 40550091.

It is an arithmetic number, because the mean of its divisors is an integer number (40550091).

Almost surely, 2^81100181 is an apocalyptic number.

It is an amenable number.

81100181 is a deficient number, since it is larger than the sum of its proper divisors (1).

81100181 is an equidigital number, since it uses as much as digits as its factorization.

81100181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 20.

The square root of 81100181 is about 9005.5638912841. The cubic root of 81100181 is about 432.8531753863.

Adding to 81100181 its reverse (18100118), we get a palindrome (99200299).

The spelling of 81100181 in words is "eighty-one million, one hundred thousand, one hundred eighty-one".