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218681 is a prime number
BaseRepresentation
bin110101011000111001
3102002222022
4311120321
523444211
64404225
71600361
oct653071
9362868
10218681
1113a331
12a6675
13786c8
14599a1
1544bdb
hex35639

218681 has 2 divisors, whose sum is σ = 218682. Its totient is φ = 218680.

The previous prime is 218677. The next prime is 218711. The reversal of 218681 is 186812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 116281 + 102400 = 341^2 + 320^2 .

It is a cyclic number.

It is not a de Polignac number, because 218681 - 22 = 218677 is a prime.

It is a super-2 number, since 2×2186812 = 95642759522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 218681.

It is not a weakly prime, because it can be changed into another prime (218611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109340 + 109341.

It is an arithmetic number, because the mean of its divisors is an integer number (109341).

2218681 is an apocalyptic number.

It is an amenable number.

218681 is a deficient number, since it is larger than the sum of its proper divisors (1).

218681 is an equidigital number, since it uses as much as digits as its factorization.

218681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 26.

The square root of 218681 is about 467.6334034262. The cubic root of 218681 is about 60.2472207071.

The spelling of 218681 in words is "two hundred eighteen thousand, six hundred eighty-one".