81558359 has 4 divisors (see below), whose sum is σ = 81968400. Its totient is φ = 81148320.

The previous prime is 81558349. The next prime is 81558371. The reversal of 81558359 is 95385518.

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 81558359 - 2¹⁶ = 81492823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81558319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 204722 + ... + 205119.

It is an arithmetic number, because the mean of its divisors is an integer number (20492100).

Almost surely, 2^81558359 is an apocalyptic number.

81558359 is a deficient number, since it is larger than the sum of its proper divisors (410041).

81558359 is a wasteful number, since it uses less digits than its factorization.

81558359 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410040.

The product of its digits is 216000, while the sum is 44.

The square root of 81558359 is about 9030.9666702962. The cubic root of 81558359 is about 433.6667843028. Note that the first 3 decimals are identical.

The spelling of 81558359 in words is "eighty-one million, five hundred fifty-eight thousand, three hundred fifty-nine".