66640667 has 2 divisors, whose sum is σ = 66640668. Its totient is φ = 66640666.

The previous prime is 66640661. The next prime is 66640699. The reversal of 66640667 is 76604666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66640667 - 2²⁰ = 65592091 is a prime.

It is not a weakly prime, because it can be changed into another prime (66640661) 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, 33320333 + 33320334.

It is an arithmetic number, because the mean of its divisors is an integer number (33320334).

Almost surely, 2^66640667 is an apocalyptic number.

66640667 is a deficient number, since it is larger than the sum of its proper divisors (1).

66640667 is an equidigital number, since it uses as much as digits as its factorization.

66640667 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 217728, while the sum is 41.

The square root of 66640667 is about 8163.3735060942. The cubic root of 66640667 is about 405.4274144428.

The spelling of 66640667 in words is "sixty-six million, six hundred forty thousand, six hundred sixty-seven".