666219912666 has 64 divisors (see below), whose sum is σ = 1662696391680. Its totient is φ = 172890725760.

The previous prime is 666219912637. The next prime is 666219912667.

666219912666 is nontrivially palindromic in base 10.

It is not an unprimeable number, because it can be changed into a prime (666219912667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 117036 + ... + 1160231.

It is an arithmetic number, because the mean of its divisors is an integer number (25979631120).

Almost surely, 2^666219912666 is an apocalyptic number.

666219912666 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 666219912666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (831348195840).

666219912666 is an abundant number, since it is smaller than the sum of its proper divisors (996476479014).

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

666219912666 is a wasteful number, since it uses less digits than its factorization.

666219912666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1278419.

The product of its digits is 15116544, while the sum is 60.

The spelling of 666219912666 in words is "six hundred sixty-six billion, two hundred nineteen million, nine hundred twelve thousand, six hundred sixty-six".