81359559 has 24 divisors (see below), whose sum is σ = 125179600. Its totient is φ = 52767936.

The previous prime is 81359557. The next prime is 81359563. The reversal of 81359559 is 95595318.

81359559 is a `hidden beast` number, since 8 + 1 + 3 + 595 + 59 = 666.

It is not a de Polignac number, because 81359559 - 2¹ = 81359557 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 (81359557) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4467 + ... + 13515.

Almost surely, 2^81359559 is an apocalyptic number.

81359559 is a deficient number, since it is larger than the sum of its proper divisors (43820041).

81359559 is an equidigital number, since it uses as much as digits as its factorization.

81359559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9101 (or 9089 counting only the distinct ones).

The product of its digits is 243000, while the sum is 45.

The square root of 81359559 is about 9019.9533812543. The cubic root of 81359559 is about 433.3141407016.

It can be divided in two parts, 81359 and 559, that added together give a palindrome (81918).

The spelling of 81359559 in words is "eighty-one million, three hundred fifty-nine thousand, five hundred fifty-nine".