666278 has 4 divisors (see below), whose sum is σ = 999420. Its totient is φ = 333138.

The previous prime is 666277. The next prime is 666301. The reversal of 666278 is 872666.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166568 + ... + 166571.

It is an arithmetic number, because the mean of its divisors is an integer number (249855).

2⁶⁶⁶²⁷⁸ is an apocalyptic number.

666278 is a deficient number, since it is larger than the sum of its proper divisors (333142).

666278 is a wasteful number, since it uses less digits than its factorization.

666278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333141.

The product of its digits is 24192, while the sum is 35.

The square root of 666278 is about 816.2585374745. The cubic root of 666278 is about 87.3410665931.

The spelling of 666278 in words is "six hundred sixty-six thousand, two hundred seventy-eight".