666878 has 4 divisors (see below), whose sum is σ = 1000320. Its totient is φ = 333438.

The previous prime is 666871. The next prime is 666889. The reversal of 666878 is 878666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166718 + ... + 166721.

It is an arithmetic number, because the mean of its divisors is an integer number (250080).

2⁶⁶⁶⁸⁷⁸ is an apocalyptic number.

666878 is a deficient number, since it is larger than the sum of its proper divisors (333442).

666878 is a wasteful number, since it uses less digits than its factorization.

666878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333441.

The product of its digits is 96768, while the sum is 41.

The square root of 666878 is about 816.6259853813. The cubic root of 666878 is about 87.3672763320.

The spelling of 666878 in words is "six hundred sixty-six thousand, eight hundred seventy-eight".