666838872 has 128 divisors (see below), whose sum is σ = 2241561600. Its totient is φ = 179311104.

The previous prime is 666838871. The next prime is 666838927. The reversal of 666838872 is 278838666.

It is a happy number.

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666838871) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12733 + ... + 38675.

It is an arithmetic number, because the mean of its divisors is an integer number (17512200).

Almost surely, 2^666838872 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 666838872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1120780800).

666838872 is an abundant number, since it is smaller than the sum of its proper divisors (1574722728).

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

666838872 is a wasteful number, since it uses less digits than its factorization.

666838872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25982 (or 25972 counting only the distinct ones).

The product of its digits is 4644864, while the sum is 54.

The square root of 666838872 is about 25823.2235013369. The cubic root of 666838872 is about 873.6556758684.

The spelling of 666838872 in words is "six hundred sixty-six million, eight hundred thirty-eight thousand, eight hundred seventy-two".