66078709 has 2 divisors, whose sum is σ = 66078710. Its totient is φ = 66078708.

The previous prime is 66078703. The next prime is 66078721. The reversal of 66078709 is 90787066.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53333809 + 12744900 = 7303^2 + 3570^2 .

It is a cyclic number.

It is not a de Polignac number, because 66078709 - 2⁹ = 66078197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66078703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33039354 + 33039355.

It is an arithmetic number, because the mean of its divisors is an integer number (33039355).

Almost surely, 2^66078709 is an apocalyptic number.

It is an amenable number.

66078709 is a deficient number, since it is larger than the sum of its proper divisors (1).

66078709 is an equidigital number, since it uses as much as digits as its factorization.

66078709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 127008, while the sum is 43.

The square root of 66078709 is about 8128.8811653265. The cubic root of 66078709 is about 404.2845856988.

The spelling of 66078709 in words is "sixty-six million, seventy-eight thousand, seven hundred nine".