643944238 has 32 divisors (see below), whose sum is σ = 1166423040. Its totient is φ = 260457120.

The previous prime is 643944211. The next prime is 643944239. The reversal of 643944238 is 832449346.

It is a junction number, because it is equal to n+sod(n) for n = 643944194 and 643944203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643944239) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67620 + ... + 76552.

It is an arithmetic number, because the mean of its divisors is an integer number (36450720).

Almost surely, 2^643944238 is an apocalyptic number.

643944238 is a deficient number, since it is larger than the sum of its proper divisors (522478802).

643944238 is a wasteful number, since it uses less digits than its factorization.

643944238 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9232.

The product of its digits is 497664, while the sum is 43.

The square root of 643944238 is about 25376.0563918037. The cubic root of 643944238 is about 863.5405856273.

It can be divided in two parts, 6439 and 44238, that multiplied together give a palindrome (284848482).

The spelling of 643944238 in words is "six hundred forty-three million, nine hundred forty-four thousand, two hundred thirty-eight".