644709929 has 2 divisors, whose sum is σ = 644709930. Its totient is φ = 644709928.

The previous prime is 644709917. The next prime is 644709973. The reversal of 644709929 is 929907446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 612810025 + 31899904 = 24755^2 + 5648^2 .

It is a cyclic number.

It is not a de Polignac number, because 644709929 - 2⁴ = 644709913 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644709029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322354964 + 322354965.

It is an arithmetic number, because the mean of its divisors is an integer number (322354965).

Almost surely, 2^644709929 is an apocalyptic number.

It is an amenable number.

644709929 is a deficient number, since it is larger than the sum of its proper divisors (1).

644709929 is an equidigital number, since it uses as much as digits as its factorization.

644709929 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 979776, while the sum is 50.

The square root of 644709929 is about 25391.1387889555. The cubic root of 644709929 is about 863.8827184378.

The spelling of 644709929 in words is "six hundred forty-four million, seven hundred nine thousand, nine hundred twenty-nine".