666777798 has 16 divisors (see below), whose sum is σ = 1481728560. Its totient is φ = 222259248.

The previous prime is 666777781. The next prime is 666777799. The reversal of 666777798 is 897777666.

It is a super-3 number, since 3×666777798³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666777799) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 6173815 + ... + 6173922.

It is an arithmetic number, because the mean of its divisors is an integer number (92608035).

Almost surely, 2^666777798 is an apocalyptic number.

666777798 is an abundant number, since it is smaller than the sum of its proper divisors (814950762).

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

666777798 is a wasteful number, since it uses less digits than its factorization.

666777798 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12347748 (or 12347742 counting only the distinct ones).

The product of its digits is 37340352, while the sum is 63.

The square root of 666777798 is about 25822.0409340548. The cubic root of 666777798 is about 873.6290031202.

The spelling of 666777798 in words is "six hundred sixty-six million, seven hundred seventy-seven thousand, seven hundred ninety-eight".