666749840 has 40 divisors (see below), whose sum is σ = 1552668480. Its totient is φ = 266274176.

The previous prime is 666749813. The next prime is 666749851. The reversal of 666749840 is 48947666.

It is a tau number, because it is divible by the number of its divisors (40).

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 7 ways as a sum of consecutive naturals, for example, 46397 + ... + 59043.

It is an arithmetic number, because the mean of its divisors is an integer number (38816712).

Almost surely, 2^666749840 is an apocalyptic number.

It is an amenable number.

666749840 is an abundant number, since it is smaller than the sum of its proper divisors (885918640).

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

666749840 is a wasteful number, since it uses less digits than its factorization.

666749840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13319 (or 13313 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 50.

The square root of 666749840 is about 25821.4995691575. The cubic root of 666749840 is about 873.6167925252.

The spelling of 666749840 in words is "six hundred sixty-six million, seven hundred forty-nine thousand, eight hundred forty".