218461 has 2 divisors, whose sum is σ = 218462.
Its totient is φ = 218460.
The previous prime is 218459. The next prime is 218479. The reversal of 218461 is 164812.
218461 = 3302 + 3312.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 109561 + 108900 = 331^2 + 330^2
It is a cyclic number.
It is not a de Polignac number, because 218461 - 21 = 218459 is a prime.
Together with 218459, it forms a pair of twin primes.
It is equal to p19480 and since 218461 and 19480 have the same sum of digits, it is a Honaker prime.
It is a plaindrome in base 16.
It is a nialpdrome in base 12.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (218401) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109230 + 109231.
It is an arithmetic number, because the mean of its divisors is an integer number (109231).
2218461 is an apocalyptic number.
218461 is the 331-st centered square number.
It is an amenable number.
218461 is a deficient number, since it is larger than the sum of its proper divisors (1).
218461 is an equidigital number, since it uses as much as digits as its factorization.
218461 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 384, while the sum is 22.
The square root of 218461 is about 467.3981172405.
The cubic root of 218461 is about 60.2270103919.
The spelling of 218461 in words is "two hundred eighteen thousand, four hundred sixty-one".