111581 has 2 divisors, whose sum is σ = 111582.
Its totient is φ = 111580.
The previous prime is 111577. The next prime is 111593. The reversal of 111581 is 185111.
Adding to 111581 its reverse (185111), we get a palindrome (296692).
It can be divided in two parts, 11 and 1581, that multiplied together give a triangular number (17391 = T186).
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 111556 + 25 = 334^2 + 5^2
It is a cyclic number.
It is not a de Polignac number, because 111581 - 22 = 111577 is a prime.
It is a super-2 number, since 2×1115812 = 24900639122, which contains 22 as substring.
It is a Chen prime.
It is a nialpdrome in base 7.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (111521) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55790 + 55791.
It is an arithmetic number, because the mean of its divisors is an integer number (55791).
2111581 is an apocalyptic number.
It is an amenable number.
111581 is a deficient number, since it is larger than the sum of its proper divisors (1).
111581 is an equidigital number, since it uses as much as digits as its factorization.
111581 is an evil number, because the sum of its binary digits is even.
The product of its digits is 40, while the sum is 17.
The square root of 111581 is about 334.0374230532.
The cubic root of 111581 is about 48.1426600728.
The spelling of 111581 in words is "one hundred eleven thousand, five hundred eighty-one".