644967361 has 2 divisors, whose sum is σ = 644967362. Its totient is φ = 644967360.

The previous prime is 644967347. The next prime is 644967383. The reversal of 644967361 is 163769446.

It is a happy number.

644967361 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 616280625 + 28686736 = 24825^2 + 5356^2 .

It is a cyclic number.

It is not a de Polignac number, because 644967361 - 2¹¹ = 644965313 is a prime.

It is not a weakly prime, because it can be changed into another prime (644967161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322483680 + 322483681.

It is an arithmetic number, because the mean of its divisors is an integer number (322483681).

Almost surely, 2^644967361 is an apocalyptic number.

It is an amenable number.

644967361 is a deficient number, since it is larger than the sum of its proper divisors (1).

644967361 is an equidigital number, since it uses as much as digits as its factorization.

644967361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 653184, while the sum is 46.

The square root of 644967361 is about 25396.2076105863. The cubic root of 644967361 is about 863.9976856255.

The spelling of 644967361 in words is "six hundred forty-four million, nine hundred sixty-seven thousand, three hundred sixty-one".