667999 has 2 divisors, whose sum is σ = 668000. Its totient is φ = 667998.

The previous prime is 667991. The next prime is 668009. The reversal of 667999 is 999766.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 667999 - 2³ = 667991 is a prime.

667999 is a modest number, since divided by 999 gives 667 as remainder.

It is a plaindrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333999 + 334000.

It is an arithmetic number, because the mean of its divisors is an integer number (334000).

2⁶⁶⁷⁹⁹⁹ is an apocalyptic number.

667999 is a deficient number, since it is larger than the sum of its proper divisors (1).

667999 is an equidigital number, since it uses as much as digits as its factorization.

667999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 183708, while the sum is 46.

The square root of 667999 is about 817.3120579069. The cubic root of 667999 is about 87.4162027677.

The spelling of 667999 in words is "six hundred sixty-seven thousand, nine hundred ninety-nine".