66571909 has 2 divisors, whose sum is σ = 66571910. Its totient is φ = 66571908.

The previous prime is 66571891. The next prime is 66571919. The reversal of 66571909 is 90917566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64160100 + 2411809 = 8010^2 + 1553^2 .

It is a cyclic number.

It is not a de Polignac number, because 66571909 - 2⁷ = 66571781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66571919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33285954 + 33285955.

It is an arithmetic number, because the mean of its divisors is an integer number (33285955).

Almost surely, 2^66571909 is an apocalyptic number.

It is an amenable number.

66571909 is a deficient number, since it is larger than the sum of its proper divisors (1).

66571909 is an equidigital number, since it uses as much as digits as its factorization.

66571909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 102060, while the sum is 43.

The square root of 66571909 is about 8159.1610475588. The cubic root of 66571909 is about 405.2879301895.

The spelling of 66571909 in words is "sixty-six million, five hundred seventy-one thousand, nine hundred nine".