81540 has 48 divisors (see below), whose sum is σ = 255360. Its totient is φ = 21600.

The previous prime is 81533. The next prime is 81547. The reversal of 81540 is 4518.

It is an interprime number because it is at equal distance from previous prime (81533) and next prime (81547).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81540.

It is not an unprimeable number, because it can be changed into a prime (81547) 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, 465 + ... + 615.

It is an arithmetic number, because the mean of its divisors is an integer number (5320).

2⁸¹⁵⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127680).

81540 is an abundant number, since it is smaller than the sum of its proper divisors (173820).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81540 is a wasteful number, since it uses less digits than its factorization.

81540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 161 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 81540 is about 285.5520968230. The cubic root of 81540 is about 43.3634242018.

The spelling of 81540 in words is "eighty-one thousand, five hundred forty".