644553000 has 384 divisors, whose sum is σ = 2684747520. Its totient is φ = 135820800.

The previous prime is 644552999. The next prime is 644553031. The reversal of 644553000 is 355446.

It is a super-3 number, since 3×644553000³ (a number of 27 digits) contains 333 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 818607 + ... + 819393.

It is an arithmetic number, because the mean of its divisors is an integer number (6991530).

Almost surely, 2^644553000 is an apocalyptic number.

644553000 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 644553000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1342373760).

644553000 is an abundant number, since it is smaller than the sum of its proper divisors (2040194520).

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

644553000 is a wasteful number, since it uses less digits than its factorization.

644553000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 834 (or 817 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 27.

The square root of 644553000 is about 25388.0483692623. The cubic root of 644553000 is about 863.8126201160.

The spelling of 644553000 in words is "six hundred forty-four million, five hundred fifty-three thousand".