644700289 has 2 divisors, whose sum is σ = 644700290. Its totient is φ = 644700288.

The previous prime is 644700283. The next prime is 644700313. The reversal of 644700289 is 982007446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 511528689 + 133171600 = 22617^2 + 11540^2 .

It is a cyclic number.

It is not a de Polignac number, because 644700289 - 2¹⁵ = 644667521 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644700283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322350144 + 322350145.

It is an arithmetic number, because the mean of its divisors is an integer number (322350145).

Almost surely, 2^644700289 is an apocalyptic number.

It is an amenable number.

644700289 is a deficient number, since it is larger than the sum of its proper divisors (1).

644700289 is an equidigital number, since it uses as much as digits as its factorization.

644700289 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96768, while the sum is 40.

The square root of 644700289 is about 25390.9489582410. The cubic root of 644700289 is about 863.8784126921.

The spelling of 644700289 in words is "six hundred forty-four million, seven hundred thousand, two hundred eighty-nine".