216664 has 32 divisors (see below), whose sum is σ = 479520. Its totient is φ = 89856.

The previous prime is 216661. The next prime is 216679. The reversal of 216664 is 466612.

216664 = T₇₀ + T₇₁ + ... + T₁₁₇.

It is a happy number.

216664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2932 + ... + 3004.

It is an arithmetic number, because the mean of its divisors is an integer number (14985).

2²¹⁶⁶⁶⁴ 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 216664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (239760).

216664 is an abundant number, since it is smaller than the sum of its proper divisors (262856).

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

216664 is a wasteful number, since it uses less digits than its factorization.

216664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139 (or 135 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 216664 is about 465.4718036573. The cubic root of 216664 is about 60.0614185893.

The spelling of 216664 in words is "two hundred sixteen thousand, six hundred sixty-four".