115861 has 2 divisors, whose sum is σ = 115862. Its totient is φ = 115860.

The previous prime is 115859. The next prime is 115873. The reversal of 115861 is 168511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62500 + 53361 = 250^2 + 231^2 .

It is a cyclic number.

It is not a de Polignac number, because 115861 - 2¹ = 115859 is a prime.

Together with 115859, it forms a pair of twin primes.

115861 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (115811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57930 + 57931.

It is an arithmetic number, because the mean of its divisors is an integer number (57931).

2¹¹⁵⁸⁶¹ is an apocalyptic number.

It is an amenable number.

115861 is a deficient number, since it is larger than the sum of its proper divisors (1).

115861 is an equidigital number, since it uses as much as digits as its factorization.

115861 is an evil number, because the sum of its binary digits is even.

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

The square root of 115861 is about 340.3836071258. The cubic root of 115861 is about 48.7505018576.

Subtracting 115861 from its reverse (168511), we obtain a triangular number (52650 = T₃₂₄).

The spelling of 115861 in words is "one hundred fifteen thousand, eight hundred sixty-one".