66639539 has 2 divisors, whose sum is σ = 66639540. Its totient is φ = 66639538.

The previous prime is 66639527. The next prime is 66639563. The reversal of 66639539 is 93593666.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66639539 - 2⁴ = 66639523 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 66639493 and 66639502.

It is not a weakly prime, because it can be changed into another prime (66639509) 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, 33319769 + 33319770.

It is an arithmetic number, because the mean of its divisors is an integer number (33319770).

Almost surely, 2^66639539 is an apocalyptic number.

66639539 is a deficient number, since it is larger than the sum of its proper divisors (1).

66639539 is an equidigital number, since it uses as much as digits as its factorization.

66639539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 787320, while the sum is 47.

The square root of 66639539 is about 8163.3044167175. The cubic root of 66639539 is about 405.4251269272.

The spelling of 66639539 in words is "sixty-six million, six hundred thirty-nine thousand, five hundred thirty-nine".