66791909 has 2 divisors, whose sum is σ = 66791910. Its totient is φ = 66791908.

The previous prime is 66791899. The next prime is 66791939. The reversal of 66791909 is 90919766.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65044225 + 1747684 = 8065^2 + 1322^2 .

It is a cyclic number.

It is not a de Polignac number, because 66791909 - 2²⁰ = 65743333 is a prime.

It is a super-2 number, since 2×66791909² = 8922318215728562, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66791939) 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, 33395954 + 33395955.

It is an arithmetic number, because the mean of its divisors is an integer number (33395955).

Almost surely, 2^66791909 is an apocalyptic number.

It is an amenable number.

66791909 is a deficient number, since it is larger than the sum of its proper divisors (1).

66791909 is an equidigital number, since it uses as much as digits as its factorization.

66791909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 183708, while the sum is 47.

The square root of 66791909 is about 8172.6317058828. The cubic root of 66791909 is about 405.7338905885.

The spelling of 66791909 in words is "sixty-six million, seven hundred ninety-one thousand, nine hundred nine".