9666781 has 2 divisors, whose sum is σ = 9666782. Its totient is φ = 9666780.

The previous prime is 9666779. The next prime is 9666799. The reversal of 9666781 is 1876669.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9665881 + 900 = 3109^2 + 30^2 .

It is an emirp because it is prime and its reverse (1876669) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9666781 - 2¹ = 9666779 is a prime.

It is a super-2 number, since 2×9666781² = 186893309803922, which contains 22 as substring.

Together with 9666779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9696781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4833390 + 4833391.

It is an arithmetic number, because the mean of its divisors is an integer number (4833391).

Almost surely, 2^9666781 is an apocalyptic number.

It is an amenable number.

9666781 is a deficient number, since it is larger than the sum of its proper divisors (1).

9666781 is an equidigital number, since it uses as much as digits as its factorization.

9666781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 43.

The square root of 9666781 is about 3109.1447377052. The cubic root of 9666781 is about 213.0233907909.

The spelling of 9666781 in words is "nine million, six hundred sixty-six thousand, seven hundred eighty-one".