666897 has 16 divisors (see below), whose sum is σ = 1108992. Its totient is φ = 346320.

The previous prime is 666889. The next prime is 666901. The reversal of 666897 is 798666.

666897 = T₆₃ + T₆₄ + ... + T₁₆₁.

It is a happy number.

It is not a de Polignac number, because 666897 - 2³ = 666889 is a prime.

666897 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (666857) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1213 + ... + 1674.

It is an arithmetic number, because the mean of its divisors is an integer number (69312).

2⁶⁶⁶⁸⁹⁷ is an apocalyptic number.

It is an amenable number.

666897 is a deficient number, since it is larger than the sum of its proper divisors (442095).

666897 is a wasteful number, since it uses less digits than its factorization.

666897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2908.

The product of its digits is 108864, while the sum is 42.

The square root of 666897 is about 816.6376185310. The cubic root of 666897 is about 87.3681060502.

Subtracting 666897 from its reverse (798666), we obtain a square (131769 = 363²).

The spelling of 666897 in words is "six hundred sixty-six thousand, eight hundred ninety-seven".