81544 has 8 divisors (see below), whose sum is σ = 152910. Its totient is φ = 40768.

The previous prime is 81533. The next prime is 81547. The reversal of 81544 is 44518.

It can be written as a sum of positive squares in only one way, i.e., 62500 + 19044 = 250^2 + 138^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

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 as a sum of consecutive naturals, namely, 5089 + ... + 5104.

2⁸¹⁵⁴⁴ is an apocalyptic number.

It is an amenable number.

81544 is a deficient number, since it is larger than the sum of its proper divisors (71366).

81544 is a wasteful number, since it uses less digits than its factorization.

81544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10199 (or 10195 counting only the distinct ones).

The product of its digits is 640, while the sum is 22.

The square root of 81544 is about 285.5591007130. The cubic root of 81544 is about 43.3641332643.

It can be divided in two parts, 81 and 544, that added together give a 4-th power (625 = 5⁴).

The spelling of 81544 in words is "eighty-one thousand, five hundred forty-four".