81523 has 4 divisors (see below), whose sum is σ = 87808. Its totient is φ = 75240.

The previous prime is 81517. The next prime is 81527. The reversal of 81523 is 32518.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81523 - 2¹³ = 73331 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81523.

It is not an unprimeable number, because it can be changed into a prime (81527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3123 + ... + 3148.

It is an arithmetic number, because the mean of its divisors is an integer number (21952).

2⁸¹⁵²³ is an apocalyptic number.

81523 is a deficient number, since it is larger than the sum of its proper divisors (6285).

81523 is a wasteful number, since it uses less digits than its factorization.

81523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6284.

The product of its digits is 240, while the sum is 19.

The square root of 81523 is about 285.5223283738. The cubic root of 81523 is about 43.3604104276.

It can be divided in two parts, 815 and 23, that added together give a palindrome (838).

The spelling of 81523 in words is "eighty-one thousand, five hundred twenty-three".