647891689 has 2 divisors, whose sum is σ = 647891690. Its totient is φ = 647891688.

The previous prime is 647891633. The next prime is 647891701. The reversal of 647891689 is 986198746.

647891689 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 379587289 + 268304400 = 19483^2 + 16380^2 .

It is a cyclic number.

It is not a de Polignac number, because 647891689 - 2⁹ = 647891177 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (647891789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323945844 + 323945845.

It is an arithmetic number, because the mean of its divisors is an integer number (323945845).

Almost surely, 2^647891689 is an apocalyptic number.

It is an amenable number.

647891689 is a deficient number, since it is larger than the sum of its proper divisors (1).

647891689 is an equidigital number, since it uses as much as digits as its factorization.

647891689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5225472, while the sum is 58.

The square root of 647891689 is about 25453.7166048497. The cubic root of 647891689 is about 865.3015260741.

The spelling of 647891689 in words is "six hundred forty-seven million, eight hundred ninety-one thousand, six hundred eighty-nine".