644723072 has 32 divisors (see below), whose sum is σ = 1467898320. Its totient is φ = 276309504.

The previous prime is 644723071. The next prime is 644723077. The reversal of 644723072 is 270327446.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644723071) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 358883 + ... + 360674.

Almost surely, 2^644723072 is an apocalyptic number.

It is an amenable number.

644723072 is an abundant number, since it is smaller than the sum of its proper divisors (823175248).

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

644723072 is an equidigital number, since it uses as much as digits as its factorization.

644723072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 719578 (or 719566 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 35.

The square root of 644723072 is about 25391.3975983993. The cubic root of 644723072 is about 863.8885887436. Note that the first 3 decimals are identical.

The spelling of 644723072 in words is "six hundred forty-four million, seven hundred twenty-three thousand, seventy-two".