644463623501 has 16 divisors (see below), whose sum is σ = 709660440000. Its totient is φ = 582867686016.

The previous prime is 644463623467. The next prime is 644463623509. The reversal of 644463623501 is 105326364446.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644463623501 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644463623509) 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 in 15 ways as a sum of consecutive naturals, for example, 6521891 + ... + 6619968.

It is an arithmetic number, because the mean of its divisors is an integer number (44353777500).

Almost surely, 2^644463623501 is an apocalyptic number.

It is an amenable number.

644463623501 is a deficient number, since it is larger than the sum of its proper divisors (65196816499).

644463623501 is a wasteful number, since it uses less digits than its factorization.

644463623501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13141996.

The product of its (nonzero) digits is 1244160, while the sum is 44.

Adding to 644463623501 its reverse (105326364446), we get a palindrome (749789987947).

The spelling of 644463623501 in words is "six hundred forty-four billion, four hundred sixty-three million, six hundred twenty-three thousand, five hundred one".