66601709 has 2 divisors, whose sum is σ = 66601710. Its totient is φ = 66601708.

The previous prime is 66601697. The next prime is 66601741. The reversal of 66601709 is 90710666.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63282025 + 3319684 = 7955^2 + 1822^2 .

It is a cyclic number.

It is not a de Polignac number, because 66601709 - 2⁴ = 66601693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66601789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33300854 + 33300855.

It is an arithmetic number, because the mean of its divisors is an integer number (33300855).

Almost surely, 2^66601709 is an apocalyptic number.

It is an amenable number.

66601709 is a deficient number, since it is larger than the sum of its proper divisors (1).

66601709 is an equidigital number, since it uses as much as digits as its factorization.

66601709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 66601709 is about 8160.9870113853. The cubic root of 66601709 is about 405.3483950254.

The spelling of 66601709 in words is "sixty-six million, six hundred one thousand, seven hundred nine".