66005609 has 2 divisors, whose sum is σ = 66005610. Its totient is φ = 66005608.

The previous prime is 66005591. The next prime is 66005623. The reversal of 66005609 is 90650066.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61152400 + 4853209 = 7820^2 + 2203^2 .

It is a cyclic number.

It is not a de Polignac number, because 66005609 - 2²⁴ = 49228393 is a prime.

It is not a weakly prime, because it can be changed into another prime (66005629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33002804 + 33002805.

It is an arithmetic number, because the mean of its divisors is an integer number (33002805).

Almost surely, 2^66005609 is an apocalyptic number.

It is an amenable number.

66005609 is a deficient number, since it is larger than the sum of its proper divisors (1).

66005609 is an equidigital number, since it uses as much as digits as its factorization.

66005609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 66005609 is about 8124.3836073883. The cubic root of 66005609 is about 404.1354498770.

The spelling of 66005609 in words is "sixty-six million, five thousand, six hundred nine".