666657 has 8 divisors (see below), whose sum is σ = 987680. Its totient is φ = 444420.

The previous prime is 666649. The next prime is 666667. The reversal of 666657 is 756666.

It is not a de Polignac number, because 666657 - 2³ = 666649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12319 + ... + 12372.

It is an arithmetic number, because the mean of its divisors is an integer number (123460).

2⁶⁶⁶⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

666657 is a deficient number, since it is larger than the sum of its proper divisors (321023).

666657 is a wasteful number, since it uses less digits than its factorization.

666657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24700 (or 24694 counting only the distinct ones).

The product of its digits is 45360, while the sum is 36.

The square root of 666657 is about 816.4906613061. The cubic root of 666657 is about 87.3576242410.

Subtracting 666657 from its reverse (756666), we obtain a palindrome (90009).

The spelling of 666657 in words is "six hundred sixty-six thousand, six hundred fifty-seven".