666390789 has 6 divisors (see below), whose sum is σ = 962564486. Its totient is φ = 444260520.

The previous prime is 666390763. The next prime is 666390839. The reversal of 666390789 is 987093666.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 532224900 + 134165889 = 23070^2 + 11583^2 .

It is not a de Polignac number, because 666390789 - 2¹³ = 666382597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666390709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 37021702 + ... + 37021719.

Almost surely, 2^666390789 is an apocalyptic number.

It is an amenable number.

666390789 is a deficient number, since it is larger than the sum of its proper divisors (296173697).

666390789 is a wasteful number, since it uses less digits than its factorization.

666390789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74043427 (or 74043424 counting only the distinct ones).

The product of its (nonzero) digits is 2939328, while the sum is 54.

The square root of 666390789 is about 25814.5460738708. The cubic root of 666390789 is about 873.4599474406.

The spelling of 666390789 in words is "six hundred sixty-six million, three hundred ninety thousand, seven hundred eighty-nine".