666551880 has 192 divisors, whose sum is σ = 2228428800. Its totient is φ = 172730880.

The previous prime is 666551869. The next prime is 666551917. The reversal of 666551880 is 88155666.

666551880 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2788801 + ... + 2789039.

It is an arithmetic number, because the mean of its divisors is an integer number (11606400).

Almost surely, 2^666551880 is an apocalyptic number.

666551880 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666551880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1114214400).

666551880 is an abundant number, since it is smaller than the sum of its proper divisors (1561876920).

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

666551880 is a wasteful number, since it uses less digits than its factorization.

666551880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 444 (or 437 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The square root of 666551880 is about 25817.6660447841. Note that the first 3 decimals coincide. The cubic root of 666551880 is about 873.5303241636.

The spelling of 666551880 in words is "six hundred sixty-six million, five hundred fifty-one thousand, eight hundred eighty".