666871440 has 160 divisors (see below), whose sum is σ = 2130935040. Its totient is φ = 172443648.

The previous prime is 666871409. The next prime is 666871463. The reversal of 666871440 is 44178666.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 666871392 and 666871401.

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, 1309906 + ... + 1310414.

It is an arithmetic number, because the mean of its divisors is an integer number (13318344).

Almost surely, 2^666871440 is an apocalyptic number.

666871440 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 666871440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1065467520).

666871440 is an abundant number, since it is smaller than the sum of its proper divisors (1464063600).

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

666871440 is a wasteful number, since it uses less digits than its factorization.

666871440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681 (or 675 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 42.

The square root of 666871440 is about 25823.8540888071. The cubic root of 666871440 is about 873.6698985719.

The spelling of 666871440 in words is "six hundred sixty-six million, eight hundred seventy-one thousand, four hundred forty".