644216280 has 128 divisors (see below), whose sum is σ = 2069280000. Its totient is φ = 159957504.

The previous prime is 644216249. The next prime is 644216297. The reversal of 644216280 is 82612446.

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 31 ways as a sum of consecutive naturals, for example, 132126 + ... + 136914.

It is an arithmetic number, because the mean of its divisors is an integer number (16166250).

Almost surely, 2^644216280 is an apocalyptic number.

644216280 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644216280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1034640000).

644216280 is an abundant number, since it is smaller than the sum of its proper divisors (1425063720).

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

644216280 is a wasteful number, since it uses less digits than its factorization.

644216280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4881 (or 4877 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 33.

The square root of 644216280 is about 25381.4160361474. The cubic root of 644216280 is about 863.6621728810.

It can be divided in two parts, 6442 and 16280, that added together give a palindrome (22722).

The spelling of 644216280 in words is "six hundred forty-four million, two hundred sixteen thousand, two hundred eighty".