218945 has 4 divisors (see below), whose sum is σ = 262740. Its totient is φ = 175152.

The previous prime is 218941. The next prime is 218947. The reversal of 218945 is 549812.

218945 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 135424 + 83521 = 368^2 + 289^2 .

It is a cyclic number.

It is not a de Polignac number, because 218945 - 2² = 218941 is a prime.

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 (218941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21890 + ... + 21899.

It is an arithmetic number, because the mean of its divisors is an integer number (65685).

2²¹⁸⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

218945 is a deficient number, since it is larger than the sum of its proper divisors (43795).

218945 is an equidigital number, since it uses as much as digits as its factorization.

218945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43794.

The product of its digits is 2880, while the sum is 29.

The square root of 218945 is about 467.9155906785. The cubic root of 218945 is about 60.2714552010.

The spelling of 218945 in words is "two hundred eighteen thousand, nine hundred forty-five".