666500778 has 32 divisors (see below), whose sum is σ = 1483749120. Its totient is φ = 221771520.

The previous prime is 666500767. The next prime is 666500909. The reversal of 666500778 is 877005666.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20463 + ... + 41853.

It is an arithmetic number, because the mean of its divisors is an integer number (46367160).

Almost surely, 2^666500778 is an apocalyptic number.

666500778 is an abundant number, since it is smaller than the sum of its proper divisors (817248342).

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

666500778 is a wasteful number, since it uses less digits than its factorization.

666500778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21979 (or 21973 counting only the distinct ones).

The product of its (nonzero) digits is 423360, while the sum is 45.

The square root of 666500778 is about 25816.6763546356. The cubic root of 666500778 is about 873.5080001762.

The spelling of 666500778 in words is "six hundred sixty-six million, five hundred thousand, seven hundred seventy-eight".