217838 has 16 divisors (see below), whose sum is σ = 356400. Its totient is φ = 99456.

The previous prime is 217829. The next prime is 217849. The reversal of 217838 is 838712.

217838 is an esthetic number in base 5, because in such base its adjacent digits differ by 1.

It is a self number, because there is not a number n which added to its sum of digits gives 217838.

It is a congruent number.

It is an unprimeable number.

217838 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1388 + ... + 1536.

It is an arithmetic number, because the mean of its divisors is an integer number (22275).

2²¹⁷⁸³⁸ is an apocalyptic number.

217838 is a deficient number, since it is larger than the sum of its proper divisors (138562).

217838 is a wasteful number, since it uses less digits than its factorization.

217838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211.

The product of its digits is 2688, while the sum is 29.

The square root of 217838 is about 466.7311860161. The cubic root of 217838 is about 60.1697047377.

The spelling of 217838 in words is "two hundred seventeen thousand, eight hundred thirty-eight".