643863826 has 16 divisors (see below), whose sum is σ = 972396288. Its totient is φ = 319737600.

The previous prime is 643863823. The next prime is 643863839. The reversal of 643863826 is 628368346.

It is not an unprimeable number, because it can be changed into a prime (643863823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 350731 + ... + 352561.

It is an arithmetic number, because the mean of its divisors is an integer number (60774768).

Almost surely, 2^643863826 is an apocalyptic number.

643863826 is a deficient number, since it is larger than the sum of its proper divisors (328532462).

643863826 is a wasteful number, since it uses less digits than its factorization.

643863826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2937.

The product of its digits is 995328, while the sum is 46.

The square root of 643863826 is about 25374.4719353921. The cubic root of 643863826 is about 863.5046394941.

The spelling of 643863826 in words is "six hundred forty-three million, eight hundred sixty-three thousand, eight hundred twenty-six".