646378321 has 2 divisors, whose sum is σ = 646378322. Its totient is φ = 646378320.

The previous prime is 646378297. The next prime is 646378339. The reversal of 646378321 is 123873646.

646378321 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., 591024721 + 55353600 = 24311^2 + 7440^2 .

It is a cyclic number.

It is not a de Polignac number, because 646378321 - 2⁵ = 646378289 is a prime.

It is a super-4 number, since 4×646378321⁴ (a number of 36 digits) contains 4444 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (646378351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323189160 + 323189161.

It is an arithmetic number, because the mean of its divisors is an integer number (323189161).

Almost surely, 2^646378321 is an apocalyptic number.

It is an amenable number.

646378321 is a deficient number, since it is larger than the sum of its proper divisors (1).

646378321 is an equidigital number, since it uses as much as digits as its factorization.

646378321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 40.

The square root of 646378321 is about 25423.9713852891. The cubic root of 646378321 is about 864.6272669891.

The spelling of 646378321 in words is "six hundred forty-six million, three hundred seventy-eight thousand, three hundred twenty-one".