217987 has 16 divisors (see below), whose sum is σ = 288000. Its totient is φ = 159840.

The previous prime is 217981. The next prime is 218003. The reversal of 217987 is 789712.

217987 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 217987 - 2³ = 217979 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 (217981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1389 + ... + 1537.

It is an arithmetic number, because the mean of its divisors is an integer number (18000).

2²¹⁷⁹⁸⁷ is an apocalyptic number.

217987 is a deficient number, since it is larger than the sum of its proper divisors (70013).

217987 is a wasteful number, since it uses less digits than its factorization.

217987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186.

The product of its digits is 7056, while the sum is 34.

The square root of 217987 is about 466.8907795192. The cubic root of 217987 is about 60.1834201940.

It can be divided in two parts, 21 and 7987, that added together give a palindrome (8008).

The spelling of 217987 in words is "two hundred seventeen thousand, nine hundred eighty-seven".