81573 has 4 divisors (see below), whose sum is σ = 108768. Its totient is φ = 54380.

The previous prime is 81569. The next prime is 81611. The reversal of 81573 is 37518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81573 - 2² = 81569 is a prime.

It is an Ulam number.

It is a D-number.

It is a Curzon number.

81573 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13593 + ... + 13598.

It is an arithmetic number, because the mean of its divisors is an integer number (27192).

2⁸¹⁵⁷³ is an apocalyptic number.

It is an amenable number.

81573 is a deficient number, since it is larger than the sum of its proper divisors (27195).

81573 is a wasteful number, since it uses less digits than its factorization.

81573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27194.

The product of its digits is 840, while the sum is 24.

The square root of 81573 is about 285.6098737789. The cubic root of 81573 is about 43.3692732738.

It can be divided in two parts, 815 and 73, that multiplied together give a palindrome (59495).

The spelling of 81573 in words is "eighty-one thousand, five hundred seventy-three".