647909 has 2 divisors, whose sum is σ = 647910. Its totient is φ = 647908.

The previous prime is 647893. The next prime is 647917. The reversal of 647909 is 909746.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 616225 + 31684 = 785^2 + 178^2 .

It is a cyclic number.

It is not a de Polignac number, because 647909 - 2⁴ = 647893 is a prime.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 647909.

It is not a weakly prime, because it can be changed into another prime (647209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323954 + 323955.

It is an arithmetic number, because the mean of its divisors is an integer number (323955).

2⁶⁴⁷⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

647909 is a deficient number, since it is larger than the sum of its proper divisors (1).

647909 is an equidigital number, since it uses as much as digits as its factorization.

647909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 647909 is about 804.9279470859. The cubic root of 647909 is about 86.5309232661.

The spelling of 647909 in words is "six hundred forty-seven thousand, nine hundred nine".