644504736 has 48 divisors (see below), whose sum is σ = 1715019264. Its totient is φ = 211889664.

The previous prime is 644504723. The next prime is 644504741. The reversal of 644504736 is 637405446.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a junction number, because it is equal to n+sod(n) for n = 644504694 and 644504703.

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 7 ways as a sum of consecutive naturals, for example, 38976 + ... + 52991.

It is an arithmetic number, because the mean of its divisors is an integer number (35729568).

Almost surely, 2^644504736 is an apocalyptic number.

It is an amenable number.

644504736 is an abundant number, since it is smaller than the sum of its proper divisors (1070514528).

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

644504736 is a wasteful number, since it uses less digits than its factorization.

644504736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92053 (or 92045 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 39.

The square root of 644504736 is about 25387.0978254703. The cubic root of 644504736 is about 863.7910588723.

The spelling of 644504736 in words is "six hundred forty-four million, five hundred four thousand, seven hundred thirty-six".