643666345 has 8 divisors (see below), whose sum is σ = 882742464. Its totient is φ = 441371184.

The previous prime is 643666343. The next prime is 643666351. The reversal of 643666345 is 543666346.

It is a happy number.

643666345 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643666345 - 2¹ = 643666343 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643666343) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9195199 + ... + 9195268.

It is an arithmetic number, because the mean of its divisors is an integer number (110342808).

Almost surely, 2^643666345 is an apocalyptic number.

It is an amenable number.

643666345 is a deficient number, since it is larger than the sum of its proper divisors (239076119).

643666345 is a wasteful number, since it uses less digits than its factorization.

643666345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18390479.

The product of its digits is 933120, while the sum is 43.

The square root of 643666345 is about 25370.5803047546. The cubic root of 643666345 is about 863.4163479486.

Subtracting from 643666345 its reverse (543666346), we obtain a palindrome (99999999).

The spelling of 643666345 in words is "six hundred forty-three million, six hundred sixty-six thousand, three hundred forty-five".