646909789 has 8 divisors (see below), whose sum is σ = 686113848. Its totient is φ = 607833600.

The previous prime is 646909763. The next prime is 646909841. The reversal of 646909789 is 987909646.

It can be written as a sum of positive squares in 4 ways, for example, as 128436889 + 518472900 = 11333^2 + 22770^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 646909789 - 2²⁵ = 613355357 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 (646909889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21442 + ... + 41875.

It is an arithmetic number, because the mean of its divisors is an integer number (85764231).

Almost surely, 2^646909789 is an apocalyptic number.

It is an amenable number.

646909789 is a deficient number, since it is larger than the sum of its proper divisors (39204059).

646909789 is a wasteful number, since it uses less digits than its factorization.

646909789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63935.

The product of its (nonzero) digits is 5878656, while the sum is 58.

The square root of 646909789 is about 25434.4213419531. The cubic root of 646909789 is about 864.8641746037.

The spelling of 646909789 in words is "six hundred forty-six million, nine hundred nine thousand, seven hundred eighty-nine".