6399666 has 48 divisors (see below), whose sum is σ = 17070144. Its totient is φ = 1687392.

The previous prime is 6399643. The next prime is 6399677. The reversal of 6399666 is 6669936.

It is a nude number because it is divisible by every one of its digits.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 316 + ... + 3591.

It is an arithmetic number, because the mean of its divisors is an integer number (355628).

Almost surely, 2^6399666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6399666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8535072).

6399666 is an abundant number, since it is smaller than the sum of its proper divisors (10670478).

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

6399666 is a wasteful number, since it uses less digits than its factorization.

6399666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3935 (or 3932 counting only the distinct ones).

The product of its digits is 314928, while the sum is 45.

The square root of 6399666 is about 2529.7561147273. The cubic root of 6399666 is about 185.6603235161.

The spelling of 6399666 in words is "six million, three hundred ninety-nine thousand, six hundred sixty-six".