81111 has 8 divisors (see below), whose sum is σ = 113920. Its totient is φ = 51192.

The previous prime is 81101. The next prime is 81119. The reversal of 81111 is 11118.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81111 - 2⁶ = 81047 is a prime.

It is a Duffinian number.

81111 is a modest number, since divided by 111 gives 81 as remainder.

81111 is a lucky number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81119) 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 7 ways as a sum of consecutive naturals, for example, 655 + ... + 768.

It is an arithmetic number, because the mean of its divisors is an integer number (14240).

2⁸¹¹¹¹ is an apocalyptic number.

81111 is a deficient number, since it is larger than the sum of its proper divisors (32809).

81111 is a wasteful number, since it uses less digits than its factorization.

81111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1445.

The product of its digits is 8, while the sum is 12.

The square root of 81111 is about 284.7999297753. The cubic root of 81111 is about 43.2872422488.

Adding to 81111 its reverse (11118), we get a palindrome (92229).

It can be divided in two parts, 8 and 1111, that multiplied together give a palindrome (8888).

The spelling of 81111 in words is "eighty-one thousand, one hundred eleven".