66749509 has 2 divisors, whose sum is σ = 66749510. Its totient is φ = 66749508.

The previous prime is 66749491. The next prime is 66749539. The reversal of 66749509 is 90594766.

66749509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65561409 + 1188100 = 8097^2 + 1090^2 .

It is a cyclic number.

It is not a de Polignac number, because 66749509 - 2⁵ = 66749477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66749539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33374754 + 33374755.

It is an arithmetic number, because the mean of its divisors is an integer number (33374755).

Almost surely, 2^66749509 is an apocalyptic number.

It is an amenable number.

66749509 is a deficient number, since it is larger than the sum of its proper divisors (1).

66749509 is an equidigital number, since it uses as much as digits as its factorization.

66749509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 408240, while the sum is 46.

The square root of 66749509 is about 8170.0372704168. The cubic root of 66749509 is about 405.6480181192.

It can be divided in two parts, 667 and 49509, that added together give a square (50176 = 224²).

The spelling of 66749509 in words is "sixty-six million, seven hundred forty-nine thousand, five hundred nine".