644240242042445 has 8 divisors (see below), whose sum is σ = 773851457574936. Its totient is φ = 514883415551296.

The previous prime is 644240242042387. The next prime is 644240242042457. The reversal of 644240242042445 is 544240242042446.

It can be written as a sum of positive squares in 4 ways, for example, as 8451178082281 + 635789063960164 = 2907091^2 + 25214858^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644240242042445 - 2¹⁶ = 644240241976909 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644240242042445.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63597254762 + ... + 63597264891.

It is an arithmetic number, because the mean of its divisors is an integer number (96731432196867).

Almost surely, 2^{644240242042445} is an apocalyptic number.

It is an amenable number.

644240242042445 is a deficient number, since it is larger than the sum of its proper divisors (129611215532491).

644240242042445 is a wasteful number, since it uses less digits than its factorization.

644240242042445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127194520671.

The product of its (nonzero) digits is 7864320, while the sum is 47.

Subtracting from 644240242042445 its reverse (544240242042446), we obtain a palindrome (99999999999999).

The spelling of 644240242042445 in words is "six hundred forty-four trillion, two hundred forty billion, two hundred forty-two million, forty-two thousand, four hundred forty-five".