644198724 has 288 divisors, whose sum is σ = 2007290880. Its totient is φ = 177292800.

The previous prime is 644198719. The next prime is 644198747. The reversal of 644198724 is 427891446.

It is a self number, because there is not a number n which added to its sum of digits gives 644198724.

It is a congruent number.

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, 15712144 + ... + 15712184.

It is an arithmetic number, because the mean of its divisors is an integer number (6969760).

Almost surely, 2^644198724 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 644198724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1003645440).

644198724 is an abundant number, since it is smaller than the sum of its proper divisors (1363092156).

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

644198724 is a wasteful number, since it uses less digits than its factorization.

644198724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 109 counting only the distinct ones).

The product of its digits is 387072, while the sum is 45.

The square root of 644198724 is about 25381.0701902028. The cubic root of 644198724 is about 863.6543273839.

The spelling of 644198724 in words is "six hundred forty-four million, one hundred ninety-eight thousand, seven hundred twenty-four".