640444490449 has 2 divisors, whose sum is σ = 640444490450. Its totient is φ = 640444490448.

The previous prime is 640444490419. The next prime is 640444490503. The reversal of 640444490449 is 944094444046.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 561577878225 + 78866612224 = 749385^2 + 280832^2 .

It is a cyclic number.

It is not a de Polignac number, because 640444490449 - 2¹⁷ = 640444359377 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 640444490396 and 640444490405.

It is not a weakly prime, because it can be changed into another prime (640444490419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320222245224 + 320222245225.

It is an arithmetic number, because the mean of its divisors is an integer number (320222245225).

Almost surely, 2^640444490449 is an apocalyptic number.

It is an amenable number.

640444490449 is a deficient number, since it is larger than the sum of its proper divisors (1).

640444490449 is an equidigital number, since it uses as much as digits as its factorization.

640444490449 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7962624, while the sum is 52.

The spelling of 640444490449 in words is "six hundred forty billion, four hundred forty-four million, four hundred ninety thousand, four hundred forty-nine".