644003612220 has 48 divisors (see below), whose sum is σ = 1803448005408. Its totient is φ = 171711640320.

The previous prime is 644003612177. The next prime is 644003612281. The reversal of 644003612220 is 22216300446.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 246939 + ... + 1161458.

It is an arithmetic number, because the mean of its divisors is an integer number (37571833446).

Almost surely, 2^644003612220 is an apocalyptic number.

644003612220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644003612220 is an abundant number, since it is smaller than the sum of its proper divisors (1159444393188).

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

644003612220 is a wasteful number, since it uses less digits than its factorization.

644003612220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1416030 (or 1416028 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 30.

Adding to 644003612220 its reverse (22216300446), we get a palindrome (666219912666).

The spelling of 644003612220 in words is "six hundred forty-four billion, three million, six hundred twelve thousand, two hundred twenty".