81500 has 24 divisors (see below), whose sum is σ = 179088. Its totient is φ = 32400.

The previous prime is 81463. The next prime is 81509. The reversal of 81500 is 518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 419 + ... + 581.

It is an arithmetic number, because the mean of its divisors is an integer number (7462).

2⁸¹⁵⁰⁰ 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 81500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89544).

81500 is an abundant number, since it is smaller than the sum of its proper divisors (97588).

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

81500 is a wasteful number, since it uses less digits than its factorization.

81500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 81500 is about 285.4820484724. The cubic root of 81500 is about 43.3563323014.

The spelling of 81500 in words is "eighty-one thousand, five hundred".