644925888 has 196 divisors, whose sum is σ = 2005541328. Its totient is φ = 205286400.

The previous prime is 644925887. The next prime is 644925899. The reversal of 644925888 is 888529446.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644925887) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 1072788 + ... + 1073388.

Almost surely, 2^644925888 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644925888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1002770664).

644925888 is an abundant number, since it is smaller than the sum of its proper divisors (1360615440).

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

644925888 is an equidigital number, since it uses as much as digits as its factorization.

644925888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 654 (or 629 counting only the distinct ones).

The product of its digits is 4423680, while the sum is 54.

The square root of 644925888 is about 25395.3910779102. The cubic root of 644925888 is about 863.9791661643.

The spelling of 644925888 in words is "six hundred forty-four million, nine hundred twenty-five thousand, eight hundred eighty-eight".