115561 has 2 divisors, whose sum is σ = 115562. Its totient is φ = 115560.

The previous prime is 115553. The next prime is 115571. The reversal of 115561 is 165511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67600 + 47961 = 260^2 + 219^2 .

It is an emirp because it is prime and its reverse (165511) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 115561 - 2³ = 115553 is a prime.

It is equal to p₁₀₉₁₈ and since 115561 and 10918 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (115571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57780 + 57781.

It is an arithmetic number, because the mean of its divisors is an integer number (57781).

2¹¹⁵⁵⁶¹ is an apocalyptic number.

It is an amenable number.

115561 is a deficient number, since it is larger than the sum of its proper divisors (1).

115561 is an equidigital number, since it uses as much as digits as its factorization.

115561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 150, while the sum is 19.

The square root of 115561 is about 339.9426422207. The cubic root of 115561 is about 48.7083887745.

It can be divided in two parts, 115 and 561, that added together give a palindrome (676).

The spelling of 115561 in words is "one hundred fifteen thousand, five hundred sixty-one".