8581 has 2 divisors, whose sum is σ = 8582. Its totient is φ = 8580.
The previous prime is 8573. The next prime is 8597. The reversal of 8581 is 1858.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 4356 + 4225 = 66^2 + 65^2 .
It is a cyclic number.
It is not a de Polignac number, because 8581 - 23 = 8573 is a prime.
It is a super-2 number, since 2×85812 = 147267122, which contains 22 as substring.
It is a Chen prime.
It is an alternating number because its digits alternate between even and odd.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (8501) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4290 + 4291.
It is an arithmetic number, because the mean of its divisors is an integer number (4291).
8581 is the 66-th centered square number.
It is an amenable number.
8581 is a deficient number, since it is larger than the sum of its proper divisors (1).
8581 is an equidigital number, since it uses as much as digits as its factorization.
8581 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 320, while the sum is 22.
The square root of 8581 is about 92.6336871770. The cubic root of 8581 is about 20.4728969610.
The spelling of 8581 in words is "eight thousand, five hundred eighty-one".
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