81740 has 24 divisors (see below), whose sum is σ = 177072. Its totient is φ = 31680.

The previous prime is 81737. The next prime is 81749. The reversal of 81740 is 4718.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (81749) 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, 1187 + ... + 1253.

It is an arithmetic number, because the mean of its divisors is an integer number (7378).

2⁸¹⁷⁴⁰ is an apocalyptic number.

It is an amenable number.

81740 is an abundant number, since it is smaller than the sum of its proper divisors (95332).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88536).

81740 is a wasteful number, since it uses less digits than its factorization.

81740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137 (or 135 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 81740 is about 285.9020811397. The cubic root of 81740 is about 43.3988489576.

The spelling of 81740 in words is "eighty-one thousand, seven hundred forty".