666747844 has 48 divisors (see below), whose sum is σ = 1395491328. Its totient is φ = 272757888.

The previous prime is 666747839. The next prime is 666747847. The reversal of 666747844 is 448747666.

666747844 = 3423² + 3424² + ... + 3478².

It is a junction number, because it is equal to n+sod(n) for n = 666747791 and 666747800.

It is not an unprimeable number, because it can be changed into a prime (666747847) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 48837 + ... + 60979.

It is an arithmetic number, because the mean of its divisors is an integer number (29072736).

Almost surely, 2^666747844 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 666747844, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (697745664).

666747844 is an abundant number, since it is smaller than the sum of its proper divisors (728743484).

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

666747844 is a wasteful number, since it uses less digits than its factorization.

666747844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12244 (or 12242 counting only the distinct ones).

The product of its digits is 5419008, while the sum is 52.

The square root of 666747844 is about 25821.4609191657. The cubic root of 666747844 is about 873.6159207635.

The spelling of 666747844 in words is "six hundred sixty-six million, seven hundred forty-seven thousand, eight hundred forty-four".