115781 has 2 divisors, whose sum is σ = 115782. Its totient is φ = 115780.
The previous prime is 115777. The next prime is 115783. The reversal of 115781 is 187511.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 111556 + 4225 = 334^2 + 65^2 .
It is a cyclic number.
It is not a de Polignac number, because 115781 - 22 = 115777 is a prime.
It is a super-2 number, since 2×1157812 = 26810479922, which contains 22 as substring.
It is a Sophie Germain prime.
Together with 115783, it forms a pair of twin primes.
It is a Chen prime.
It is a Curzon number.
It is a plaindrome in base 15.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (115783) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57890 + 57891.
It is an arithmetic number, because the mean of its divisors is an integer number (57891).
2115781 is an apocalyptic number.
It is an amenable number.
115781 is a deficient number, since it is larger than the sum of its proper divisors (1).
115781 is an equidigital number, since it uses as much as digits as its factorization.
115781 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 280, while the sum is 23.
The square root of 115781 is about 340.2660723610. The cubic root of 115781 is about 48.7392788170.
The spelling of 115781 in words is "one hundred fifteen thousand, seven hundred eighty-one".
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