643666306 has 16 divisors (see below), whose sum is σ = 1025316000. Its totient is φ = 302194368.

The previous prime is 643666301. The next prime is 643666307. The reversal of 643666306 is 603666346.

It is not an unprimeable number, because it can be changed into a prime (643666301) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 70656 + ... + 79243.

It is an arithmetic number, because the mean of its divisors is an integer number (64082250).

Almost surely, 2^643666306 is an apocalyptic number.

643666306 is a deficient number, since it is larger than the sum of its proper divisors (381649694).

643666306 is a wasteful number, since it uses less digits than its factorization.

643666306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150033.

The product of its (nonzero) digits is 279936, while the sum is 40.

The square root of 643666306 is about 25370.5795361478. The cubic root of 643666306 is about 863.4163305104.

Adding to 643666306 its sum of digits (40), we get a palindrome (643666346).

The spelling of 643666306 in words is "six hundred forty-three million, six hundred sixty-six thousand, three hundred six".