644020529 has 2 divisors, whose sum is σ = 644020530. Its totient is φ = 644020528.

The previous prime is 644020513. The next prime is 644020583. The reversal of 644020529 is 925020446.

644020529 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., 614296225 + 29724304 = 24785^2 + 5452^2 .

It is a cyclic number.

It is not a de Polignac number, because 644020529 - 2⁴ = 644020513 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644020495 and 644020504.

It is not a weakly prime, because it can be changed into another prime (644020829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322010264 + 322010265.

It is an arithmetic number, because the mean of its divisors is an integer number (322010265).

Almost surely, 2^644020529 is an apocalyptic number.

It is an amenable number.

644020529 is a deficient number, since it is larger than the sum of its proper divisors (1).

644020529 is an equidigital number, since it uses as much as digits as its factorization.

644020529 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 644020529 is about 25377.5595556389. The cubic root of 644020529 is about 863.5746868064.

The spelling of 644020529 in words is "six hundred forty-four million, twenty thousand, five hundred twenty-nine".