644240242042446 has 128 divisors (see below), whose sum is σ = 1518504199520256. Its totient is φ = 178437602764800.

The previous prime is 644240242042387. The next prime is 644240242042457.

644240242042446 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 644240242042395 and 644240242042404.

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 63 ways as a sum of consecutive naturals, for example, 34831411 + ... + 50017073.

It is an arithmetic number, because the mean of its divisors is an integer number (11863314058752).

Almost surely, 2^{644240242042446} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644240242042446, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (759252099760128).

644240242042446 is an abundant number, since it is smaller than the sum of its proper divisors (874263957477810).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644240242042446 is a wasteful number, since it uses less digits than its factorization.

644240242042446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15185986.

The product of its (nonzero) digits is 9437184, while the sum is 48.

The spelling of 644240242042446 in words is "six hundred forty-four trillion, two hundred forty billion, two hundred forty-two million, forty-two thousand, four hundred forty-six".