644608493 has 2 divisors, whose sum is σ = 644608494. Its totient is φ = 644608492.

The previous prime is 644608441. The next prime is 644608507. The reversal of 644608493 is 394806446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 326235844 + 318372649 = 18062^2 + 17843^2 .

It is a cyclic number.

It is not a de Polignac number, because 644608493 - 2⁶ = 644608429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644608403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322304246 + 322304247.

It is an arithmetic number, because the mean of its divisors is an integer number (322304247).

Almost surely, 2^644608493 is an apocalyptic number.

It is an amenable number.

644608493 is a deficient number, since it is larger than the sum of its proper divisors (1).

644608493 is an equidigital number, since it uses as much as digits as its factorization.

644608493 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 497664, while the sum is 44.

The square root of 644608493 is about 25389.1412418774. The cubic root of 644608493 is about 863.8374094807.

The spelling of 644608493 in words is "six hundred forty-four million, six hundred eight thousand, four hundred ninety-three".