218545 has 8 divisors (see below), whose sum is σ = 265320. Its totient is φ = 172800.

The previous prime is 218531. The next prime is 218549. The reversal of 218545 is 545812.

It can be written as a sum of positive squares in 4 ways, for example, as 104976 + 113569 = 324^2 + 337^2 .

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

It is not a de Polignac number, because 218545 - 2⁵ = 218513 is a prime.

It is an Ulam number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218549) 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, 345 + ... + 745.

It is an arithmetic number, because the mean of its divisors is an integer number (33165).

2²¹⁸⁵⁴⁵ is an apocalyptic number.

It is an amenable number.

218545 is a deficient number, since it is larger than the sum of its proper divisors (46775).

218545 is a wasteful number, since it uses less digits than its factorization.

218545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515.

The product of its digits is 1600, while the sum is 25.

The square root of 218545 is about 467.4879677596. The cubic root of 218545 is about 60.2347286583.

The spelling of 218545 in words is "two hundred eighteen thousand, five hundred forty-five".