6668778666 has 32 divisors (see below), whose sum is σ = 15405951168. Its totient is φ = 1901968640.

The previous prime is 6668778643. The next prime is 6668778667.

6668778666 is nontrivially palindromic in base 10.

It is a super-3 number, since 3×6668778666³ (a number of 30 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a junction number, because it is equal to n+sod(n) for n = 6668778597 and 6668778606.

It is not an unprimeable number, because it can be changed into a prime (6668778667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2970705 + ... + 2972948.

It is an arithmetic number, because the mean of its divisors is an integer number (481435974).

Almost surely, 2^6668778666 is an apocalyptic number.

6668778666 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

6668778666 is an abundant number, since it is smaller than the sum of its proper divisors (8737172502).

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

6668778666 is a wasteful number, since it uses less digits than its factorization.

6668778666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5943686.

The product of its digits is 146313216, while the sum is 66.

The square root of 6668778666 is about 81662.5903703771. The cubic root of 6668778666 is about 1882.2707835247.

The spelling of 6668778666 in words is "six billion, six hundred sixty-eight million, seven hundred seventy-eight thousand, six hundred sixty-six".