218161 has 8 divisors (see below), whose sum is σ = 237384. Its totient is φ = 199680.

The previous prime is 218149. The next prime is 218171. The reversal of 218161 is 161812.

218161 = T₂₈ + T₂₉ + ... + T₁₀₉.

218161 = 63² + 64² + ... + 96².

It can be written as a sum of positive squares in 4 ways, for example, as 1936 + 216225 = 44^2 + 465^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 218161 - 2¹¹ = 216113 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218111) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 541 + ... + 853.

It is an arithmetic number, because the mean of its divisors is an integer number (29673).

2²¹⁸¹⁶¹ is an apocalyptic number.

It is an amenable number.

218161 is a deficient number, since it is larger than the sum of its proper divisors (19223).

218161 is a wasteful number, since it uses less digits than its factorization.

218161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371.

The product of its digits is 96, while the sum is 19.

The square root of 218161 is about 467.0770814330. The cubic root of 218161 is about 60.1994289928.

Adding to 218161 its reverse (161812), we get a palindrome (379973).

The spelling of 218161 in words is "two hundred eighteen thousand, one hundred sixty-one".