666541644 has 96 divisors (see below), whose sum is σ = 1698278400. Its totient is φ = 202675200.

The previous prime is 666541607. The next prime is 666541663. The reversal of 666541644 is 446145666.

It is a junction number, because it is equal to n+sod(n) for n = 666541596 and 666541605.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 950494 + ... + 951194.

It is an arithmetic number, because the mean of its divisors is an integer number (17690400).

Almost surely, 2^666541644 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 666541644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (849139200).

666541644 is an abundant number, since it is smaller than the sum of its proper divisors (1031736756).

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

666541644 is a wasteful number, since it uses less digits than its factorization.

666541644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 863 (or 861 counting only the distinct ones).

The product of its digits is 414720, while the sum is 42.

The square root of 666541644 is about 25817.4678076685. The cubic root of 666541644 is about 873.5258526427.

The spelling of 666541644 in words is "six hundred sixty-six million, five hundred forty-one thousand, six hundred forty-four".