643143668 has 6 divisors (see below), whose sum is σ = 1125501426. Its totient is φ = 321571832.

The previous prime is 643143667. The next prime is 643143691. The reversal of 643143668 is 866341346.

It can be written as a sum of positive squares in only one way, i.e., 474455524 + 168688144 = 21782^2 + 12988^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643143667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80392955 + ... + 80392962.

It is an arithmetic number, because the mean of its divisors is an integer number (187583571).

Almost surely, 2^643143668 is an apocalyptic number.

It is an amenable number.

643143668 is a deficient number, since it is larger than the sum of its proper divisors (482357758).

643143668 is a wasteful number, since it uses less digits than its factorization.

643143668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160785921 (or 160785919 counting only the distinct ones).

The product of its digits is 248832, while the sum is 41.

The square root of 643143668 is about 25360.2773644138. The cubic root of 643143668 is about 863.1825777257.

The spelling of 643143668 in words is "six hundred forty-three million, one hundred forty-three thousand, six hundred sixty-eight".