81110681 has 2 divisors, whose sum is σ = 81110682. Its totient is φ = 81110680.

The previous prime is 81110657. The next prime is 81110699. The reversal of 81110681 is 18601118.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73685056 + 7425625 = 8584^2 + 2725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81110681 is a prime.

It is a super-2 number, since 2×81110681² = 13157885144567522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81110681.

It is not a weakly prime, because it can be changed into another prime (81110611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40555340 + 40555341.

It is an arithmetic number, because the mean of its divisors is an integer number (40555341).

Almost surely, 2^81110681 is an apocalyptic number.

It is an amenable number.

81110681 is a deficient number, since it is larger than the sum of its proper divisors (1).

81110681 is an equidigital number, since it uses as much as digits as its factorization.

81110681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 26.

The square root of 81110681 is about 9006.1468453496. The cubic root of 81110681 is about 432.8718550085.

Adding to 81110681 its reverse (18601118), we get a palindrome (99711799).

The spelling of 81110681 in words is "eighty-one million, one hundred ten thousand, six hundred eighty-one".