115681 has 4 divisors (see below), whose sum is σ = 119700. Its totient is φ = 111664.

The previous prime is 115679. The next prime is 115693. The reversal of 115681 is 186511.

115681 = 240² + 241².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186511 = 13 ⋅14347.

It can be written as a sum of positive squares in 2 ways, for example, as 57600 + 58081 = 240^2 + 241^2 .

It is a cyclic number.

It is not a de Polignac number, because 115681 - 2¹ = 115679 is a prime.

It is a super-2 number, since 2×115681² = 26764187522, which contains 22 as substring.

It is a Duffinian number.

115681 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (115601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1966 + ... + 2023.

It is an arithmetic number, because the mean of its divisors is an integer number (29925).

2¹¹⁵⁶⁸¹ is an apocalyptic number.

115681 is the 241-st centered square number.

It is an amenable number.

115681 is a deficient number, since it is larger than the sum of its proper divisors (4019).

115681 is an equidigital number, since it uses as much as digits as its factorization.

115681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4018.

The product of its digits is 240, while the sum is 22.

The square root of 115681 is about 340.1190967882. The cubic root of 115681 is about 48.7252427439.

Adding to 115681 its product of digits (240), we get a triangular number (115921 = T₄₈₁).

It can be divided in two parts, 1156 and 81, that multiplied together give a square (93636 = 306²).

The spelling of 115681 in words is "one hundred fifteen thousand, six hundred eighty-one".