643673636 has 12 divisors (see below), whose sum is σ = 1129107420. Its totient is φ = 321071520.

The previous prime is 643673633. The next prime is 643673683. The reversal of 643673636 is 636376346.

It is a happy number.

643673636 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 17172736 + 626500900 = 4144^2 + 25030^2 .

It is not an unprimeable number, because it can be changed into a prime (643673633) 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, 189431 + ... + 192798.

It is an arithmetic number, because the mean of its divisors is an integer number (94092285).

Almost surely, 2^643673636 is an apocalyptic number.

It is an amenable number.

643673636 is a deficient number, since it is larger than the sum of its proper divisors (485433784).

643673636 is a wasteful number, since it uses less digits than its factorization.

643673636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 382654 (or 382652 counting only the distinct ones).

The product of its digits is 979776, while the sum is 44.

The square root of 643673636 is about 25370.7239943995. The cubic root of 643673636 is about 863.4196079942.

The spelling of 643673636 in words is "six hundred forty-three million, six hundred seventy-three thousand, six hundred thirty-six".