644420505049 has 2 divisors, whose sum is σ = 644420505050. Its totient is φ = 644420505048.

The previous prime is 644420504957. The next prime is 644420505073. The reversal of 644420505049 is 940505024446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 633030279424 + 11390225625 = 795632^2 + 106725^2 .

It is a cyclic number.

It is not a de Polignac number, because 644420505049 - 2⁷ = 644420504921 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644420504996 and 644420505014.

It is not a weakly prime, because it can be changed into another prime (644420505149) 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, 322210252524 + 322210252525.

It is an arithmetic number, because the mean of its divisors is an integer number (322210252525).

Almost surely, 2^644420505049 is an apocalyptic number.

It is an amenable number.

644420505049 is a deficient number, since it is larger than the sum of its proper divisors (1).

644420505049 is an equidigital number, since it uses as much as digits as its factorization.

644420505049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 691200, while the sum is 43.

The spelling of 644420505049 in words is "six hundred forty-four billion, four hundred twenty million, five hundred five thousand, forty-nine".