667391 has 4 divisors (see below), whose sum is σ = 696432. Its totient is φ = 638352.

The previous prime is 667379. The next prime is 667417. The reversal of 667391 is 193766.

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

It is a cyclic number.

It is not a de Polignac number, because 667391 - 2¹⁸ = 405247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14486 + ... + 14531.

It is an arithmetic number, because the mean of its divisors is an integer number (174108).

2⁶⁶⁷³⁹¹ is an apocalyptic number.

667391 is a deficient number, since it is larger than the sum of its proper divisors (29041).

667391 is a wasteful number, since it uses less digits than its factorization.

667391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29040.

The product of its digits is 6804, while the sum is 32.

The square root of 667391 is about 816.9400222783. The cubic root of 667391 is about 87.3896731947.

The spelling of 667391 in words is "six hundred sixty-seven thousand, three hundred ninety-one".