667591 has 4 divisors (see below), whose sum is σ = 685672. Its totient is φ = 649512.

The previous prime is 667577. The next prime is 667631. The reversal of 667591 is 195766.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 195766 = 2 ⋅97883.

It is a cyclic number.

It is not a de Polignac number, because 667591 - 2⁵ = 667559 is a prime.

It is a pancake number, because a pancake can be divided into 667591 parts by 1155 straight cuts.

It is a Duffinian number.

It is a plaindrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667501) 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, 8985 + ... + 9058.

It is an arithmetic number, because the mean of its divisors is an integer number (171418).

2⁶⁶⁷⁵⁹¹ is an apocalyptic number.

667591 is a deficient number, since it is larger than the sum of its proper divisors (18081).

667591 is a wasteful number, since it uses less digits than its factorization.

667591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18080.

The product of its digits is 11340, while the sum is 34.

The square root of 667591 is about 817.0624211160. The cubic root of 667591 is about 87.3984018056.

The spelling of 667591 in words is "six hundred sixty-seven thousand, five hundred ninety-one".