666777788 has 6 divisors (see below), whose sum is σ = 1166861136. Its totient is φ = 333388892.

The previous prime is 666777781. The next prime is 666777799. The reversal of 666777788 is 887777666.

It is a super-3 number, since 3×666777788³ (a number of 27 digits) contains 333 as substring.

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 666777788.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666777781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83347220 + ... + 83347227.

It is an arithmetic number, because the mean of its divisors is an integer number (194476856).

Almost surely, 2^666777788 is an apocalyptic number.

It is an amenable number.

666777788 is a deficient number, since it is larger than the sum of its proper divisors (500083348).

666777788 is a wasteful number, since it uses less digits than its factorization.

666777788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166694451 (or 166694449 counting only the distinct ones).

The product of its digits is 33191424, while the sum is 62.

The square root of 666777788 is about 25822.0407404217. The cubic root of 666777788 is about 873.6289987528.

The spelling of 666777788 in words is "six hundred sixty-six million, seven hundred seventy-seven thousand, seven hundred eighty-eight".