66616609 has 2 divisors, whose sum is σ = 66616610. Its totient is φ = 66616608.

The previous prime is 66616597. The next prime is 66616621. The reversal of 66616609 is 90661666.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (66616597) and next prime (66616621).

It can be written as a sum of positive squares in only one way, i.e., 51624225 + 14992384 = 7185^2 + 3872^2 .

It is a cyclic number.

It is not a de Polignac number, because 66616609 - 2⁵ = 66616577 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66616699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33308304 + 33308305.

It is an arithmetic number, because the mean of its divisors is an integer number (33308305).

Almost surely, 2^66616609 is an apocalyptic number.

It is an amenable number.

66616609 is a deficient number, since it is larger than the sum of its proper divisors (1).

66616609 is an equidigital number, since it uses as much as digits as its factorization.

66616609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 66616609 is about 8161.8998401108. The cubic root of 66616609 is about 405.3786206799.

The spelling of 66616609 in words is "sixty-six million, six hundred sixteen thousand, six hundred nine".