81115 has 4 divisors (see below), whose sum is σ = 97344. Its totient is φ = 64888.

The previous prime is 81101. The next prime is 81119. The reversal of 81115 is 51118.

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 81115 - 2⁵ = 81083 is a prime.

It is a Duffinian number.

81115 is a lucky 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 3 ways as a sum of consecutive naturals, for example, 8107 + ... + 8116.

It is an arithmetic number, because the mean of its divisors is an integer number (24336).

2⁸¹¹¹⁵ is an apocalyptic number.

81115 is a deficient number, since it is larger than the sum of its proper divisors (16229).

81115 is a wasteful number, since it uses less digits than its factorization.

81115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16228.

The product of its digits is 40, while the sum is 16.

The square root of 81115 is about 284.8069521623. The cubic root of 81115 is about 43.2879538092.

It can be divided in two parts, 81 and 115, that added together give a square (196 = 14²).

The spelling of 81115 in words is "eighty-one thousand, one hundred fifteen".