646309 has 2 divisors, whose sum is σ = 646310. Its totient is φ = 646308.

The previous prime is 646307. The next prime is 646339. The reversal of 646309 is 903646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 494209 + 152100 = 703^2 + 390^2 .

It is a cyclic number.

It is not a de Polignac number, because 646309 - 2¹ = 646307 is a prime.

Together with 646307, it forms a pair of twin primes.

It is a nialpdrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646301) 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, 323154 + 323155.

It is an arithmetic number, because the mean of its divisors is an integer number (323155).

2⁶⁴⁶³⁰⁹ is an apocalyptic number.

It is an amenable number.

646309 is a deficient number, since it is larger than the sum of its proper divisors (1).

646309 is an equidigital number, since it uses as much as digits as its factorization.

646309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 646309 is about 803.9334549576. The cubic root of 646309 is about 86.4596356830.

The spelling of 646309 in words is "six hundred forty-six thousand, three hundred nine".