6639666 has 32 divisors (see below), whose sum is σ = 14990400. Its totient is φ = 1942080.

The previous prime is 6639653. The next prime is 6639679. The reversal of 6639666 is 6669366.

It is an interprime number because it is at equal distance from previous prime (6639653) and next prime (6639679).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 180 + ... + 3648.

It is an arithmetic number, because the mean of its divisors is an integer number (468450).

Almost surely, 2^6639666 is an apocalyptic number.

6639666 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 6639666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7495200).

6639666 is an abundant number, since it is smaller than the sum of its proper divisors (8350734).

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

6639666 is a wasteful number, since it uses less digits than its factorization.

6639666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3514.

The product of its digits is 209952, while the sum is 42.

The square root of 6639666 is about 2576.7549359611. The cubic root of 6639666 is about 187.9527759763.

The spelling of 6639666 in words is "six million, six hundred thirty-nine thousand, six hundred sixty-six".