644440002420 has 48 divisors (see below), whose sum is σ = 1882885576320. Its totient is φ = 164378898816.

The previous prime is 644440002413. The next prime is 644440002469. The reversal of 644440002420 is 24200044446.

644440002420 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

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, 233491375 + ... + 233494134.

It is an arithmetic number, because the mean of its divisors is an integer number (39226782840).

Almost surely, 2^644440002420 is an apocalyptic number.

644440002420 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644440002420 is an abundant number, since it is smaller than the sum of its proper divisors (1238445573900).

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

644440002420 is a wasteful number, since it uses less digits than its factorization.

644440002420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 466985544 (or 466985542 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 30.

Adding to 644440002420 its reverse (24200044446), we get a palindrome (668640046866).

The spelling of 644440002420 in words is "six hundred forty-four billion, four hundred forty million, two thousand, four hundred twenty".