644263336 has 32 divisors (see below), whose sum is σ = 1237320360. Its totient is φ = 314376192.

The previous prime is 644263313. The next prime is 644263349. The reversal of 644263336 is 633362446.

644263336 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 4 ways, for example, as 365039236 + 279224100 = 19106^2 + 16710^2 .

It is a super-2 number, since 2×644263336² = 830150492227697792, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644263295 and 644263304.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77896 + ... + 85768.

Almost surely, 2^644263336 is an apocalyptic number.

It is an amenable number.

644263336 is a deficient number, since it is larger than the sum of its proper divisors (593057024).

644263336 is a wasteful number, since it uses less digits than its factorization.

644263336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8125 (or 8121 counting only the distinct ones).

The product of its digits is 186624, while the sum is 37.

The square root of 644263336 is about 25382.3429966581. The cubic root of 644263336 is about 863.6832007558.

The spelling of 644263336 in words is "six hundred forty-four million, two hundred sixty-three thousand, three hundred thirty-six".