668778 has 16 divisors (see below), whose sum is σ = 1459296. Its totient is φ = 202640.

The previous prime is 668761. The next prime is 668791. The reversal of 668778 is 877866.

It is an unprimeable number.

668778 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5001 + ... + 5132.

It is an arithmetic number, because the mean of its divisors is an integer number (91206).

2⁶⁶⁸⁷⁷⁸ is an apocalyptic number.

668778 is an abundant number, since it is smaller than the sum of its proper divisors (790518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

668778 is a wasteful number, since it uses less digits than its factorization.

668778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10149.

The product of its digits is 112896, while the sum is 42.

The square root of 668778 is about 817.7884812101. The cubic root of 668778 is about 87.4501702677.

The spelling of 668778 in words is "six hundred sixty-eight thousand, seven hundred seventy-eight".