666780777 has 24 divisors (see below), whose sum is σ = 1050358400. Its totient is φ = 405127008.

The previous prime is 666780769. The next prime is 666780797. The reversal of 666780777 is 777087666.

It is a happy number.

It is not a de Polignac number, because 666780777 - 2³ = 666780769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666780797) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26827 + ... + 45312.

Almost surely, 2^666780777 is an apocalyptic number.

It is an amenable number.

666780777 is a deficient number, since it is larger than the sum of its proper divisors (383577623).

666780777 is a wasteful number, since it uses less digits than its factorization.

666780777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72237 (or 72234 counting only the distinct ones).

The product of its (nonzero) digits is 4148928, while the sum is 54.

The square root of 666780777 is about 25822.0986172697. The cubic root of 666780777 is about 873.6303041718.

The spelling of 666780777 in words is "six hundred sixty-six million, seven hundred eighty thousand, seven hundred seventy-seven".