644702353 has 2 divisors, whose sum is σ = 644702354. Its totient is φ = 644702352.

The previous prime is 644702323. The next prime is 644702363. The reversal of 644702353 is 353207446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 640241809 + 4460544 = 25303^2 + 2112^2 .

It is a cyclic number.

It is not a de Polignac number, because 644702353 - 2⁵ = 644702321 is a prime.

It is a super-2 number, since 2×644702353² = 831282247927473218, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644702323) 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, 322351176 + 322351177.

It is an arithmetic number, because the mean of its divisors is an integer number (322351177).

Almost surely, 2^644702353 is an apocalyptic number.

It is an amenable number.

644702353 is a deficient number, since it is larger than the sum of its proper divisors (1).

644702353 is an equidigital number, since it uses as much as digits as its factorization.

644702353 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 34.

The square root of 644702353 is about 25390.9896026130. The cubic root of 644702353 is about 863.8793345898.

Adding to 644702353 its reverse (353207446), we get a palindrome (997909799).

The spelling of 644702353 in words is "six hundred forty-four million, seven hundred two thousand, three hundred fifty-three".