66611509 has 2 divisors, whose sum is σ = 66611510. Its totient is φ = 66611508.

The previous prime is 66611497. The next prime is 66611533. The reversal of 66611509 is 90511666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 60109009 + 6502500 = 7753^2 + 2550^2 .

It is a cyclic number.

It is not a de Polignac number, because 66611509 - 2⁹ = 66610997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66611539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33305754 + 33305755.

It is an arithmetic number, because the mean of its divisors is an integer number (33305755).

Almost surely, 2^66611509 is an apocalyptic number.

It is an amenable number.

66611509 is a deficient number, since it is larger than the sum of its proper divisors (1).

66611509 is an equidigital number, since it uses as much as digits as its factorization.

66611509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 66611509 is about 8161.5874068713. The cubic root of 66611509 is about 405.3682754935.

The spelling of 66611509 in words is "sixty-six million, six hundred eleven thousand, five hundred nine".