6665445666 has 128 divisors (see below), whose sum is σ = 16796160000. Its totient is φ = 1940823360.

The previous prime is 6665445643. The next prime is 6665445667.

6665445666 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (6665445667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4116205 + ... + 4117823.

It is an arithmetic number, because the mean of its divisors is an integer number (131220000).

Almost surely, 2^6665445666 is an apocalyptic number.

6665445666 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 6665445666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8398080000).

6665445666 is an abundant number, since it is smaller than the sum of its proper divisors (10130714334).

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

6665445666 is a wasteful number, since it uses less digits than its factorization.

6665445666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1909 (or 1903 counting only the distinct ones).

The product of its digits is 18662400, while the sum is 54.

The square root of 6665445666 is about 81642.1806788623. The cubic root of 6665445666 is about 1881.9571501848.

The spelling of 6665445666 in words is "six billion, six hundred sixty-five million, four hundred forty-five thousand, six hundred sixty-six".