644353 has 2 divisors, whose sum is σ = 644354. Its totient is φ = 644352.

The previous prime is 644341. The next prime is 644359. The reversal of 644353 is 353446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 620944 + 23409 = 788^2 + 153^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644353 is a prime.

It is not a weakly prime, because it can be changed into another prime (644359) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322176 + 322177.

It is an arithmetic number, because the mean of its divisors is an integer number (322177).

2⁶⁴⁴³⁵³ is an apocalyptic number.

It is an amenable number.

644353 is a deficient number, since it is larger than the sum of its proper divisors (1).

644353 is an equidigital number, since it uses as much as digits as its factorization.

644353 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 25.

The square root of 644353 is about 802.7160145406. The cubic root of 644353 is about 86.3723265997.

Adding to 644353 its reverse (353446), we get a palindrome (997799).

The spelling of 644353 in words is "six hundred forty-four thousand, three hundred fifty-three".