644315904 has 216 divisors, whose sum is σ = 1989098160. Its totient is φ = 205701120.

The previous prime is 644315899. The next prime is 644315909. The reversal of 644315904 is 409513446.

644315904 is a `hidden beast` number, since 64 + 4 + 3 + 1 + 590 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (644315899) and next prime (644315909).

It is a tau number, because it is divible by the number of its divisors (216).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644315909) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6642384 + ... + 6642480.

Almost surely, 2^644315904 is an apocalyptic number.

644315904 is a gapful number since it is divisible by the number (64) 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 644315904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (994549080).

644315904 is an abundant number, since it is smaller than the sum of its proper divisors (1344782256).

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

644315904 is an equidigital number, since it uses as much as digits as its factorization.

644315904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 644315904 is about 25383.3784985372. The cubic root of 644315904 is about 863.7066905625.

The spelling of 644315904 in words is "six hundred forty-four million, three hundred fifteen thousand, nine hundred four".