644602252242 has 64 divisors (see below), whose sum is σ = 1402005749760. Its totient is φ = 196400825664.

The previous prime is 644602252219. The next prime is 644602252297. The reversal of 644602252242 is 242252206446.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 644602252242.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 3331759 + ... + 3519917.

It is an arithmetic number, because the mean of its divisors is an integer number (21906339840).

Almost surely, 2^644602252242 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644602252242, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (701002874880).

644602252242 is an abundant number, since it is smaller than the sum of its proper divisors (757403497518).

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

644602252242 is a wasteful number, since it uses less digits than its factorization.

644602252242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188607.

The product of its (nonzero) digits is 368640, while the sum is 39.

Adding to 644602252242 its reverse (242252206446), we get a palindrome (886854458688).

The spelling of 644602252242 in words is "six hundred forty-four billion, six hundred two million, two hundred fifty-two thousand, two hundred forty-two".