668756978 has 8 divisors (see below), whose sum is σ = 1003287168. Its totient is φ = 334327924.

The previous prime is 668756951. The next prime is 668756983. The reversal of 668756978 is 879657866.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 668756978.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5726 + ... + 37017.

It is an arithmetic number, because the mean of its divisors is an integer number (125410896).

Almost surely, 2^668756978 is an apocalyptic number.

668756978 is a deficient number, since it is larger than the sum of its proper divisors (334530190).

668756978 is a wasteful number, since it uses less digits than its factorization.

668756978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50568.

The product of its digits is 30481920, while the sum is 62.

The square root of 668756978 is about 25860.3359993640. The cubic root of 668756978 is about 874.4925397121.

The spelling of 668756978 in words is "six hundred sixty-eight million, seven hundred fifty-six thousand, nine hundred seventy-eight".