81597523 has 4 divisors (see below), whose sum is σ = 93254320. Its totient is φ = 69940728.

The previous prime is 81597511. The next prime is 81597547. The reversal of 81597523 is 32579518.

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 81597523 - 2¹³ = 81589331 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81597553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5828388 + ... + 5828401.

It is an arithmetic number, because the mean of its divisors is an integer number (23313580).

Almost surely, 2^81597523 is an apocalyptic number.

81597523 is a deficient number, since it is larger than the sum of its proper divisors (11656797).

81597523 is a wasteful number, since it uses less digits than its factorization.

81597523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11656796.

The product of its digits is 75600, while the sum is 40.

The square root of 81597523 is about 9033.1347272140. The cubic root of 81597523 is about 433.7361882172.

The spelling of 81597523 in words is "eighty-one million, five hundred ninety-seven thousand, five hundred twenty-three".