66523409 has 2 divisors, whose sum is σ = 66523410. Its totient is φ = 66523408.

The previous prime is 66523403. The next prime is 66523411. The reversal of 66523409 is 90432566.

66523409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 36240400 + 30283009 = 6020^2 + 5503^2 .

It is a cyclic number.

It is not a de Polignac number, because 66523409 - 2⁴ = 66523393 is a prime.

It is a Sophie Germain prime.

Together with 66523411, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (66523403) 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, 33261704 + 33261705.

It is an arithmetic number, because the mean of its divisors is an integer number (33261705).

Almost surely, 2^66523409 is an apocalyptic number.

It is an amenable number.

66523409 is a deficient number, since it is larger than the sum of its proper divisors (1).

66523409 is an equidigital number, since it uses as much as digits as its factorization.

66523409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 35.

The square root of 66523409 is about 8156.1883867405. The cubic root of 66523409 is about 405.1894840615.

The spelling of 66523409 in words is "sixty-six million, five hundred twenty-three thousand, four hundred nine".