6689681 has 2 divisors, whose sum is σ = 6689682. Its totient is φ = 6689680.

The previous prime is 6689659. The next prime is 6689689. The reversal of 6689681 is 1869866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4774225 + 1915456 = 2185^2 + 1384^2 .

It is a cyclic number.

It is not a de Polignac number, because 6689681 - 2¹⁰ = 6688657 is a prime.

It is a super-2 number, since 2×6689681² = 89503663763522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (6689689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3344840 + 3344841.

It is an arithmetic number, because the mean of its divisors is an integer number (3344841).

Almost surely, 2^6689681 is an apocalyptic number.

It is an amenable number.

6689681 is a deficient number, since it is larger than the sum of its proper divisors (1).

6689681 is an equidigital number, since it uses as much as digits as its factorization.

6689681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 124416, while the sum is 44.

The square root of 6689681 is about 2586.4417642777. The cubic root of 6689681 is about 188.4235302072.

The spelling of 6689681 in words is "six million, six hundred eighty-nine thousand, six hundred eighty-one".