666722789 has 4 divisors (see below), whose sum is σ = 689713260. Its totient is φ = 643732320.

The previous prime is 666722773. The next prime is 666722801. The reversal of 666722789 is 987227666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 269517889 + 397204900 = 16417^2 + 19930^2 .

It is a cyclic number.

It is not a de Polignac number, because 666722789 - 2⁴ = 666722773 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 666722789.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666722759) 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, 11495192 + ... + 11495249.

It is an arithmetic number, because the mean of its divisors is an integer number (172428315).

Almost surely, 2^666722789 is an apocalyptic number.

It is an amenable number.

666722789 is a deficient number, since it is larger than the sum of its proper divisors (22990471).

666722789 is a wasteful number, since it uses less digits than its factorization.

666722789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22990470.

The product of its digits is 3048192, while the sum is 53.

The square root of 666722789 is about 25820.9757561561. The cubic root of 666722789 is about 873.6049777355.

The spelling of 666722789 in words is "six hundred sixty-six million, seven hundred twenty-two thousand, seven hundred eighty-nine".