644347456 has 63 divisors (see below), whose sum is σ = 1357594059. Its totient is φ = 303389568.

The previous prime is 644347441. The next prime is 644347523. The reversal of 644347456 is 654743446.

It is a happy number.

The square root of 644347456 is 25384.

It is a perfect power (a square), and thus also a powerful number.

644347456 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Duffinian number.

Its product of digits (967680) is a multiple of the sum of its prime factors (384).

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3858285 + ... + 3858451.

Almost surely, 2^644347456 is an apocalyptic number.

644347456 is the 25384-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644347456

644347456 is an abundant number, since it is smaller than the sum of its proper divisors (713246603).

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

644347456 is an equidigital number, since it uses as much as digits as its factorization.

644347456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384 (or 188 counting only the distinct ones).

The product of its digits is 967680, while the sum is 43.

The cubic root of 644347456 is about 863.7207888376.

It can be divided in two parts, 644 and 347456, that added together give a square (348100 = 590²).

The spelling of 644347456 in words is "six hundred forty-four million, three hundred forty-seven thousand, four hundred fifty-six".