667712681 has 4 divisors (see below), whose sum is σ = 667836372. Its totient is φ = 667588992.

The previous prime is 667712671. The next prime is 667712699. The reversal of 667712681 is 186217766.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 31866025 + 635846656 = 5645^2 + 25216^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-667712681 is a prime.

It is a super-2 number, since 2×667712681² = 891680448736415522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (667712651) 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 in 3 ways as a sum of consecutive naturals, for example, 53360 + ... + 64673.

It is an arithmetic number, because the mean of its divisors is an integer number (166959093).

Almost surely, 2^667712681 is an apocalyptic number.

It is an amenable number.

667712681 is a deficient number, since it is larger than the sum of its proper divisors (123691).

667712681 is a wasteful number, since it uses less digits than its factorization.

667712681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123690.

The product of its digits is 169344, while the sum is 44.

The square root of 667712681 is about 25840.1370158906. The cubic root of 667712681 is about 874.0371148320.

The spelling of 667712681 in words is "six hundred sixty-seven million, seven hundred twelve thousand, six hundred eighty-one".