218081 has 2 divisors, whose sum is σ = 218082. Its totient is φ = 218080.
The previous prime is 218077. The next prime is 218083. The reversal of 218081 is 180812.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 160000 + 58081 = 400^2 + 241^2 .
It is a cyclic number.
It is not a de Polignac number, because 218081 - 22 = 218077 is a prime.
It is a super-2 number, since 2×2180812 = 95118645122, which contains 22 as substring.
Together with 218083, it forms a pair of twin primes.
It is a Chen prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (218083) by changing a digit.
It is a good prime.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109040 + 109041.
It is an arithmetic number, because the mean of its divisors is an integer number (109041).
2218081 is an apocalyptic number.
It is an amenable number.
218081 is a deficient number, since it is larger than the sum of its proper divisors (1).
218081 is an equidigital number, since it uses as much as digits as its factorization.
218081 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 128, while the sum is 20.
The square root of 218081 is about 466.9914346110. The cubic root of 218081 is about 60.1920696831.
Adding to 218081 its reverse (180812), we get a palindrome (398893).
The spelling of 218081 in words is "two hundred eighteen thousand, eighty-one".
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