666627778 has 8 divisors (see below), whose sum is σ = 1001564172. Its totient is φ = 332773056.

The previous prime is 666627769. The next prime is 666627781. The reversal of 666627778 is 877726666.

It can be written as a sum of positive squares in 2 ways, for example, as 612414009 + 54213769 = 24747^2 + 7363^2 .

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

It is a super-3 number, since 3×666627778³ (a number of 27 digits) contains 333 as substring.

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, 268875 + ... + 271342.

Almost surely, 2^666627778 is an apocalyptic number.

666627778 is a deficient number, since it is larger than the sum of its proper divisors (334936394).

666627778 is a wasteful number, since it uses less digits than its factorization.

666627778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540836.

The product of its digits is 7112448, while the sum is 55.

The square root of 666627778 is about 25819.1358879417. The cubic root of 666627778 is about 873.5634782163.

The spelling of 666627778 in words is "six hundred sixty-six million, six hundred twenty-seven thousand, seven hundred seventy-eight".