66817589 has 2 divisors, whose sum is σ = 66817590. Its totient is φ = 66817588.

The previous prime is 66817519. The next prime is 66817591. The reversal of 66817589 is 98571866.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61105489 + 5712100 = 7817^2 + 2390^2 .

It is a cyclic number.

It is not a de Polignac number, because 66817589 - 2¹⁶ = 66752053 is a prime.

It is a Sophie Germain prime.

Together with 66817591, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66817519) 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, 33408794 + 33408795.

It is an arithmetic number, because the mean of its divisors is an integer number (33408795).

Almost surely, 2^66817589 is an apocalyptic number.

It is an amenable number.

66817589 is a deficient number, since it is larger than the sum of its proper divisors (1).

66817589 is an equidigital number, since it uses as much as digits as its factorization.

66817589 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 50.

The square root of 66817589 is about 8174.2026522469. The cubic root of 66817589 is about 405.7858824711.

The spelling of 66817589 in words is "sixty-six million, eight hundred seventeen thousand, five hundred eighty-nine".