66839917 has 2 divisors, whose sum is σ = 66839918. Its totient is φ = 66839916.

The previous prime is 66839873. The next prime is 66839959. The reversal of 66839917 is 71993866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53670276 + 13169641 = 7326^2 + 3629^2 .

It is a cyclic number.

It is not a de Polignac number, because 66839917 - 2¹⁹ = 66315629 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 (66839987) 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, 33419958 + 33419959.

It is an arithmetic number, because the mean of its divisors is an integer number (33419959).

Almost surely, 2^66839917 is an apocalyptic number.

It is an amenable number.

66839917 is a deficient number, since it is larger than the sum of its proper divisors (1).

66839917 is an equidigital number, since it uses as much as digits as its factorization.

66839917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 489888, while the sum is 49.

The square root of 66839917 is about 8175.5682982897. The cubic root of 66839917 is about 405.8310770488.

The spelling of 66839917 in words is "sixty-six million, eight hundred thirty-nine thousand, nine hundred seventeen".