666776560 has 20 divisors (see below), whose sum is σ = 1550255688. Its totient is φ = 266710592.

The previous prime is 666776531. The next prime is 666776569. The reversal of 666776560 is 65677666.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666776569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4167274 + ... + 4167433.

Almost surely, 2^666776560 is an apocalyptic number.

It is an amenable number.

666776560 is an abundant number, since it is smaller than the sum of its proper divisors (883479128).

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

666776560 is a wasteful number, since it uses less digits than its factorization.

666776560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8334720 (or 8334714 counting only the distinct ones).

The product of its (nonzero) digits is 1905120, while the sum is 49.

The square root of 666776560 is about 25822.0169622747. The cubic root of 666776560 is about 873.6284624337.

It can be divided in two parts, 66677 and 6560, that added together give a palindrome (73237).

The spelling of 666776560 in words is "six hundred sixty-six million, seven hundred seventy-six thousand, five hundred sixty".