666355640 has 32 divisors (see below), whose sum is σ = 1501411680. Its totient is φ = 266166912.

The previous prime is 666355637. The next prime is 666355673. The reversal of 666355640 is 46553666.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17957 + ... + 40683.

It is an arithmetic number, because the mean of its divisors is an integer number (46919115).

Almost surely, 2^666355640 is an apocalyptic number.

It is an amenable number.

666355640 is an abundant number, since it is smaller than the sum of its proper divisors (835056040).

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

666355640 is a wasteful number, since it uses less digits than its factorization.

666355640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23471 (or 23467 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 41.

The square root of 666355640 is about 25813.8652665578. The cubic root of 666355640 is about 873.4445901938. Note that the first 3 decimals are identical.

The spelling of 666355640 in words is "six hundred sixty-six million, three hundred fifty-five thousand, six hundred forty".