66131909 has 2 divisors, whose sum is σ = 66131910. Its totient is φ = 66131908.

The previous prime is 66131903. The next prime is 66131929. The reversal of 66131909 is 90913166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64802500 + 1329409 = 8050^2 + 1153^2 .

It is a cyclic number.

It is not a de Polignac number, because 66131909 - 2¹² = 66127813 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66131903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33065954 + 33065955.

It is an arithmetic number, because the mean of its divisors is an integer number (33065955).

Almost surely, 2^66131909 is an apocalyptic number.

It is an amenable number.

66131909 is a deficient number, since it is larger than the sum of its proper divisors (1).

66131909 is an equidigital number, since it uses as much as digits as its factorization.

66131909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 35.

The square root of 66131909 is about 8132.1527900059. The cubic root of 66131909 is about 404.3930531656.

The spelling of 66131909 in words is "sixty-six million, one hundred thirty-one thousand, nine hundred nine".