643605911 has 12 divisors (see below), whose sum is σ = 719409600. Its totient is φ = 574928640.

The previous prime is 643605889. The next prime is 643605923. The reversal of 643605911 is 119506346.

It is not a de Polignac number, because 643605911 - 2⁶ = 643605847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643605931) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56186 + ... + 66663.

It is an arithmetic number, because the mean of its divisors is an integer number (59950800).

Almost surely, 2^643605911 is an apocalyptic number.

643605911 is a deficient number, since it is larger than the sum of its proper divisors (75803689).

643605911 is a wasteful number, since it uses less digits than its factorization.

643605911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122906 (or 122893 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 643605911 is about 25369.3892516158. The cubic root of 643605911 is about 863.3893249746.

The spelling of 643605911 in words is "six hundred forty-three million, six hundred five thousand, nine hundred eleven".