666915640 has 32 divisors (see below), whose sum is σ = 1502712000. Its totient is φ = 266383744.

The previous prime is 666915611. The next prime is 666915649. The reversal of 666915640 is 46519666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666915649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17166 + ... + 40354.

It is an arithmetic number, because the mean of its divisors is an integer number (46959750).

Almost surely, 2^666915640 is an apocalyptic number.

It is an amenable number.

666915640 is an abundant number, since it is smaller than the sum of its proper divisors (835796360).

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

666915640 is a wasteful number, since it uses less digits than its factorization.

666915640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23919 (or 23915 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 43.

The square root of 666915640 is about 25824.7098725233. The cubic root of 666915640 is about 873.6892003214.

The spelling of 666915640 in words is "six hundred sixty-six million, nine hundred fifteen thousand, six hundred forty".