666678385 has 4 divisors (see below), whose sum is σ = 800014068. Its totient is φ = 533342704.

The previous prime is 666678379. The next prime is 666678449. The reversal of 666678385 is 583876666.

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

It can be written as a sum of positive squares in 2 ways, for example, as 368908849 + 297769536 = 19207^2 + 17256^2 .

It is a cyclic number.

It is not a de Polignac number, because 666678385 - 2¹¹ = 666676337 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66667834 + ... + 66667843.

It is an arithmetic number, because the mean of its divisors is an integer number (200003517).

Almost surely, 2^666678385 is an apocalyptic number.

It is an amenable number.

666678385 is a deficient number, since it is larger than the sum of its proper divisors (133335683).

666678385 is a wasteful number, since it uses less digits than its factorization.

666678385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133335682.

The product of its digits is 8709120, while the sum is 55.

The square root of 666678385 is about 25820.1158982682. The cubic root of 666678385 is about 873.5855831598.

The spelling of 666678385 in words is "six hundred sixty-six million, six hundred seventy-eight thousand, three hundred eighty-five".