666986987 has 2 divisors, whose sum is σ = 666986988. Its totient is φ = 666986986.

The previous prime is 666986977. The next prime is 666987019. The reversal of 666986987 is 789689666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666986987 - 2⁶ = 666986923 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (666986977) 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 as a sum of consecutive naturals, namely, 333493493 + 333493494.

It is an arithmetic number, because the mean of its divisors is an integer number (333493494).

Almost surely, 2^666986987 is an apocalyptic number.

666986987 is a deficient number, since it is larger than the sum of its proper divisors (1).

666986987 is an equidigital number, since it uses as much as digits as its factorization.

666986987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 47029248, while the sum is 65.

The square root of 666986987 is about 25826.0912063750. The cubic root of 666986987 is about 873.7203551267.

The spelling of 666986987 in words is "six hundred sixty-six million, nine hundred eighty-six thousand, nine hundred eighty-seven".