644426204444 has 24 divisors (see below), whose sum is σ = 1283758132608. Its totient is φ = 280185305840.

The previous prime is 644426204399. The next prime is 644426204473. The reversal of 644426204444 is 444402624446.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a junction number, because it is equal to n+sod(n) for n = 644426204395 and 644426204404.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 318391382 + ... + 318393405.

It is an arithmetic number, because the mean of its divisors is an integer number (53489922192).

Almost surely, 2^644426204444 is an apocalyptic number.

It is an amenable number.

644426204444 is a deficient number, since it is larger than the sum of its proper divisors (639331928164).

644426204444 is a wasteful number, since it uses less digits than its factorization.

644426204444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 636784825 (or 636784823 counting only the distinct ones).

The product of its (nonzero) digits is 2359296, while the sum is 44.

The spelling of 644426204444 in words is "six hundred forty-four billion, four hundred twenty-six million, two hundred four thousand, four hundred forty-four".