217855 has 16 divisors (see below), whose sum is σ = 303264. Its totient is φ = 148480.

The previous prime is 217849. The next prime is 217859. The reversal of 217855 is 558712.

It is not a de Polignac number, because 217855 - 2⁵ = 217823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 819 + ... + 1051.

It is an arithmetic number, because the mean of its divisors is an integer number (18954).

2²¹⁷⁸⁵⁵ is an apocalyptic number.

217855 is a deficient number, since it is larger than the sum of its proper divisors (85409).

217855 is a wasteful number, since it uses less digits than its factorization.

217855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266.

The product of its digits is 2800, while the sum is 28.

The square root of 217855 is about 466.7493974286. The cubic root of 217855 is about 60.1712699044.

The spelling of 217855 in words is "two hundred seventeen thousand, eight hundred fifty-five".