81915 has 16 divisors (see below), whose sum is σ = 135168.
Its totient is φ = 42336.
The previous prime is 81901. The next prime is 81919. The reversal of 81915 is 51918.
It is not a de Polignac number, because 81915 - 24 = 81899 is a prime.
It is not an unprimeable number, because it can be changed into a prime (81919) by changing a digit.
It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 582 + ... + 708.
It is an arithmetic number, because the mean of its divisors is an integer number (8448).
281915 is an apocalyptic number.
81915 is a deficient number, since it is larger than the sum of its proper divisors (53253).
81915 is a wasteful number, since it uses less digits than its factorization.
81915 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 178.
The product of its digits is 360, while the sum is 24.
The square root of 81915 is about 286.2079663462.
The cubic root of 81915 is about 43.4297982481.
The spelling of 81915 in words is "eighty-one thousand, nine hundred fifteen".