643857044 has 12 divisors (see below), whose sum is σ = 1127004564. Its totient is φ = 321855744.

The previous prime is 643857037. The next prime is 643857059. The reversal of 643857044 is 440758346.

It can be written as a sum of positive squares in 2 ways, for example, as 494528644 + 149328400 = 22238^2 + 12220^2 .

It is a junction number, because it is equal to n+sod(n) for n = 643856992 and 643857010.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 4994 + ... + 36230.

It is an arithmetic number, because the mean of its divisors is an integer number (93917047).

Almost surely, 2^643857044 is an apocalyptic number.

It is an amenable number.

643857044 is a deficient number, since it is larger than the sum of its proper divisors (483147520).

643857044 is a wasteful number, since it uses less digits than its factorization.

643857044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36394 (or 36392 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 41.

The square root of 643857044 is about 25374.3382967911. The cubic root of 643857044 is about 863.5016076371.

The spelling of 643857044 in words is "six hundred forty-three million, eight hundred fifty-seven thousand, forty-four".