217305 has 24 divisors (see below), whose sum is σ = 411840. Its totient is φ = 105120.

The previous prime is 217271. The next prime is 217307. The reversal of 217305 is 503712.

217305 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 217305 - 2⁶ = 217241 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (217307) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 276 + ... + 714.

It is an arithmetic number, because the mean of its divisors is an integer number (17160).

2²¹⁷³⁰⁵ is an apocalyptic number.

It is an amenable number.

217305 is a deficient number, since it is larger than the sum of its proper divisors (194535).

217305 is a wasteful number, since it uses less digits than its factorization.

217305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461 (or 458 counting only the distinct ones).

The product of its (nonzero) digits is 210, while the sum is 18.

The square root of 217305 is about 466.1598438304. The cubic root of 217305 is about 60.1205908019.

The spelling of 217305 in words is "two hundred seventeen thousand, three hundred five".