666666729 has 12 divisors (see below), whose sum is σ = 970315632. Its totient is φ = 441051000.

The previous prime is 666666727. The next prime is 666666757. The reversal of 666666729 is 927666666.

It is not a de Polignac number, because 666666729 - 2¹ = 666666727 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666666727) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 281547 + ... + 283904.

It is an arithmetic number, because the mean of its divisors is an integer number (80859636).

Almost surely, 2^666666729 is an apocalyptic number.

It is an amenable number.

666666729 is a deficient number, since it is larger than the sum of its proper divisors (303648903).

666666729 is a wasteful number, since it uses less digits than its factorization.

666666729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 565588 (or 565585 counting only the distinct ones).

The product of its digits is 5878656, while the sum is 54.

The square root of 666666729 is about 25819.8901817959. The cubic root of 666666729 is about 873.5804919629.

The spelling of 666666729 in words is "six hundred sixty-six million, six hundred sixty-six thousand, seven hundred twenty-nine".