6517678721 has 2 divisors, whose sum is σ = 6517678722. Its totient is φ = 6517678720.

The previous prime is 6517678711. The next prime is 6517678771. The reversal of 6517678721 is 1278767156.

It is an a-pointer prime, because the next prime (6517678771) can be obtained adding 6517678721 to its sum of digits (50).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3438649600 + 3079029121 = 58640^2 + 55489^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6517678721 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 6517678721.

It is not a weakly prime, because it can be changed into another prime (6517678711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3258839360 + 3258839361.

It is an arithmetic number, because the mean of its divisors is an integer number (3258839361).

Almost surely, 2^6517678721 is an apocalyptic number.

It is an amenable number.

6517678721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6517678721 is an equidigital number, since it uses as much as digits as its factorization.

6517678721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 987840, while the sum is 50.

The square root of 6517678721 is about 80732.1418085758. The cubic root of 6517678721 is about 1867.9459961163.

The spelling of 6517678721 in words is "six billion, five hundred seventeen million, six hundred seventy-eight thousand, seven hundred twenty-one".