6690 has 16 divisors (see below), whose sum is σ = 16128. Its totient is φ = 1776.

The previous prime is 6689. The next prime is 6691. The reversal of 6690 is 966.

It is an interprime number because it is at equal distance from previous prime (6689) and next prime (6691).

It is a super-2 number, since 2×6690² = 89512200, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82 + ... + 141.

It is an arithmetic number, because the mean of its divisors is an integer number (1008).

2⁶⁶⁹⁰ is an apocalyptic number.

6690 is an abundant number, since it is smaller than the sum of its proper divisors (9438).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8064).

6690 is a wasteful number, since it uses less digits than its factorization.

6690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233.

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 6690 is about 81.7924201867. The cubic root of 6690 is about 18.8426525176.

It can be divided in two parts, 6 and 690, that added together give a palindrome (696).

The spelling of 6690 in words is "six thousand, six hundred ninety".