115581 has 8 divisors (see below), whose sum is σ = 156960. Its totient is φ = 75632.

The previous prime is 115571. The next prime is 115589. The reversal of 115581 is 185511.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 115581 - 2¹⁵ = 82813 is a prime.

It is a super-2 number, since 2×115581² = 26717935122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (115589) 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 7 ways as a sum of consecutive naturals, for example, 150 + ... + 503.

It is an arithmetic number, because the mean of its divisors is an integer number (19620).

2¹¹⁵⁵⁸¹ is an apocalyptic number.

It is an amenable number.

115581 is a deficient number, since it is larger than the sum of its proper divisors (41379).

115581 is an equidigital number, since it uses as much as digits as its factorization.

115581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 715.

The product of its digits is 200, while the sum is 21.

The square root of 115581 is about 339.9720576753. The cubic root of 115581 is about 48.7111985794.

It can be divided in two parts, 115 and 581, that added together give a palindrome (696).

The spelling of 115581 in words is "one hundred fifteen thousand, five hundred eighty-one".