666397 has 4 divisors (see below), whose sum is σ = 671616. Its totient is φ = 661180.

The previous prime is 666353. The next prime is 666403. The reversal of 666397 is 793666.

666397 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 793666 = 2 ⋅396833.

It is a cyclic number.

It is not a de Polignac number, because 666397 - 2⁷ = 666269 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 (666697) 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, 2413 + ... + 2674.

It is an arithmetic number, because the mean of its divisors is an integer number (167904).

2⁶⁶⁶³⁹⁷ is an apocalyptic number.

It is an amenable number.

666397 is a deficient number, since it is larger than the sum of its proper divisors (5219).

666397 is a wasteful number, since it uses less digits than its factorization.

666397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5218.

The product of its digits is 40824, while the sum is 37.

The square root of 666397 is about 816.3314277914. The cubic root of 666397 is about 87.3462661085.

The spelling of 666397 in words is "six hundred sixty-six thousand, three hundred ninety-seven".