647839 has 2 divisors, whose sum is σ = 647840. Its totient is φ = 647838.

The previous prime is 647837. The next prime is 647851. The reversal of 647839 is 938746.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 647839 - 2¹ = 647837 is a prime.

Together with 647837, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 647798 and 647807.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323919 + 323920.

It is an arithmetic number, because the mean of its divisors is an integer number (323920).

2⁶⁴⁷⁸³⁹ is an apocalyptic number.

647839 is a deficient number, since it is larger than the sum of its proper divisors (1).

647839 is an equidigital number, since it uses as much as digits as its factorization.

647839 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 37.

The square root of 647839 is about 804.8844637586. The cubic root of 647839 is about 86.5278068908.

The spelling of 647839 in words is "six hundred forty-seven thousand, eight hundred thirty-nine".