6691067681 has 2 divisors, whose sum is σ = 6691067682. Its totient is φ = 6691067680.

The previous prime is 6691067671. The next prime is 6691067707. The reversal of 6691067681 is 1867601966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6589380625 + 101687056 = 81175^2 + 10084^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6691067681 is a prime.

It is a super-2 number, since 2×6691067681² = 89540773423445435522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (6691067641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3345533840 + 3345533841.

It is an arithmetic number, because the mean of its divisors is an integer number (3345533841).

Almost surely, 2^6691067681 is an apocalyptic number.

It is an amenable number.

6691067681 is a deficient number, since it is larger than the sum of its proper divisors (1).

6691067681 is an equidigital number, since it uses as much as digits as its factorization.

6691067681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 653184, while the sum is 50.

The square root of 6691067681 is about 81798.9466985975. The cubic root of 6691067681 is about 1884.3654852988.

The spelling of 6691067681 in words is "six billion, six hundred ninety-one million, sixty-seven thousand, six hundred eighty-one".