6664 has 24 divisors (see below), whose sum is σ = 15390. Its totient is φ = 2688.

The previous prime is 6661. The next prime is 6673. The reversal of 6664 is 4666.

It can be written as a sum of positive squares in only one way, i.e., 4900 + 1764 = 70^2 + 42^2 .

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 384 + ... + 400.

2⁶⁶⁶⁴ 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 6664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7695).

6664 is an abundant number, since it is smaller than the sum of its proper divisors (8726).

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

6664 is a wasteful number, since it uses less digits than its factorization.

6664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37 (or 26 counting only the distinct ones).

The product of its digits is 864, while the sum is 22.

The square root of 6664 is about 81.6333265278. The cubic root of 6664 is about 18.8182108135.

It can be divided in two parts, 66 and 64, that multiplied together give a palindrome (4224).

The spelling of 6664 in words is "six thousand, six hundred sixty-four".