66819647 has 2 divisors, whose sum is σ = 66819648. Its totient is φ = 66819646.

The previous prime is 66819617. The next prime is 66819661. The reversal of 66819647 is 74691866.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66819647 - 2¹⁰ = 66818623 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 (66819617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33409823 + 33409824.

It is an arithmetic number, because the mean of its divisors is an integer number (33409824).

Almost surely, 2^66819647 is an apocalyptic number.

66819647 is a deficient number, since it is larger than the sum of its proper divisors (1).

66819647 is an equidigital number, since it uses as much as digits as its factorization.

66819647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 47.

The square root of 66819647 is about 8174.3285351153. The cubic root of 66819647 is about 405.7900485337.

The spelling of 66819647 in words is "sixty-six million, eight hundred nineteen thousand, six hundred forty-seven".