217668 has 48 divisors (see below), whose sum is σ = 592704. Its totient is φ = 61440.

The previous prime is 217667. The next prime is 217681. The reversal of 217668 is 866712.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2196 + ... + 2292.

It is an arithmetic number, because the mean of its divisors is an integer number (12348).

2²¹⁷⁶⁶⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (296352).

217668 is an abundant number, since it is smaller than the sum of its proper divisors (375036).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217668 is a wasteful number, since it uses less digits than its factorization.

217668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132 (or 130 counting only the distinct ones).

The product of its digits is 4032, while the sum is 30.

The square root of 217668 is about 466.5490327929. The cubic root of 217668 is about 60.1540485898.

It can be divided in two parts, 21 and 7668, that multiplied together give a triangular number (161028 = T₅₆₇).

The spelling of 217668 in words is "two hundred seventeen thousand, six hundred sixty-eight".