666840729 has 8 divisors (see below), whose sum is σ = 889276320. Its totient is φ = 444482816.

The previous prime is 666840673. The next prime is 666840731. The reversal of 666840729 is 927048666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 666840729 - 2¹¹ = 666838681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666840029) by changing a digit.

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, 5002 + ... + 36860.

It is an arithmetic number, because the mean of its divisors is an integer number (111159540).

Almost surely, 2^666840729 is an apocalyptic number.

It is an amenable number.

666840729 is a deficient number, since it is larger than the sum of its proper divisors (222435591).

666840729 is a wasteful number, since it uses less digits than its factorization.

666840729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38839.

The product of its (nonzero) digits is 870912, while the sum is 48.

The square root of 666840729 is about 25823.2594573187. The cubic root of 666840729 is about 873.6564868474.

The spelling of 666840729 in words is "six hundred sixty-six million, eight hundred forty thousand, seven hundred twenty-nine".