667861 has 2 divisors, whose sum is σ = 667862. Its totient is φ = 667860.

The previous prime is 667859. The next prime is 667867. The reversal of 667861 is 168766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 649636 + 18225 = 806^2 + 135^2 .

It is a cyclic number.

It is not a de Polignac number, because 667861 - 2¹ = 667859 is a prime.

Together with 667859, 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 (667867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333930 + 333931.

It is an arithmetic number, because the mean of its divisors is an integer number (333931).

2⁶⁶⁷⁸⁶¹ is an apocalyptic number.

It is an amenable number.

667861 is a deficient number, since it is larger than the sum of its proper divisors (1).

667861 is an equidigital number, since it uses as much as digits as its factorization.

667861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 34.

The square root of 667861 is about 817.2276304678. The cubic root of 667861 is about 87.4101826654.

The spelling of 667861 in words is "six hundred sixty-seven thousand, eight hundred sixty-one".