81071111 has 4 divisors (see below), whose sum is σ = 88441224. Its totient is φ = 73701000.

The previous prime is 81071077. The next prime is 81071129. The reversal of 81071111 is 11117018.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81071111 - 2¹⁸ = 80808967 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81071131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3685040 + ... + 3685061.

It is an arithmetic number, because the mean of its divisors is an integer number (22110306).

Almost surely, 2^81071111 is an apocalyptic number.

81071111 is a deficient number, since it is larger than the sum of its proper divisors (7370113).

81071111 is a wasteful number, since it uses less digits than its factorization.

81071111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7370112.

The product of its (nonzero) digits is 56, while the sum is 20.

The square root of 81071111 is about 9003.9497444177. The cubic root of 81071111 is about 432.8014511057.

Adding to 81071111 its reverse (11117018), we get a palindrome (92188129).

The spelling of 81071111 in words is "eighty-one million, seventy-one thousand, one hundred eleven".