644553556 has 12 divisors (see below), whose sum is σ = 1128314068. Its totient is φ = 322178112.

The previous prime is 644553529. The next prime is 644553557. The reversal of 644553556 is 655355446.

644553556 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 598585156 + 45968400 = 24466^2 + 6780^2 .

It is a super-3 number, since 3×644553556³ (a number of 27 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (43) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644553557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8841 + ... + 36976.

Almost surely, 2^644553556 is an apocalyptic number.

It is an amenable number.

644553556 is a deficient number, since it is larger than the sum of its proper divisors (483760512).

644553556 is a wasteful number, since it uses less digits than its factorization.

644553556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49338 (or 49336 counting only the distinct ones).

The product of its digits is 1080000, while the sum is 43.

The square root of 644553556 is about 25388.0593192942. The cubic root of 644553556 is about 863.8128684947.

The spelling of 644553556 in words is "six hundred forty-four million, five hundred fifty-three thousand, five hundred fifty-six".