644326057 has 2 divisors, whose sum is σ = 644326058. Its totient is φ = 644326056.

The previous prime is 644326051. The next prime is 644326087. The reversal of 644326057 is 750623446.

644326057 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., 640899856 + 3426201 = 25316^2 + 1851^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644326057 is a prime.

It is not a weakly prime, because it can be changed into another prime (644326051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322163028 + 322163029.

It is an arithmetic number, because the mean of its divisors is an integer number (322163029).

Almost surely, 2^644326057 is an apocalyptic number.

It is an amenable number.

644326057 is a deficient number, since it is larger than the sum of its proper divisors (1).

644326057 is an equidigital number, since it uses as much as digits as its factorization.

644326057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 37.

The square root of 644326057 is about 25383.5784908275. The cubic root of 644326057 is about 863.7112272439.

The spelling of 644326057 in words is "six hundred forty-four million, three hundred twenty-six thousand, fifty-seven".