643611011 has 4 divisors (see below), whose sum is σ = 646115592. Its totient is φ = 641106432.

The previous prime is 643610993. The next prime is 643611019. The reversal of 643611011 is 110116346.

643611011 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643611011 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643611019) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1251905 + ... + 1252418.

It is an arithmetic number, because the mean of its divisors is an integer number (161528898).

Almost surely, 2^643611011 is an apocalyptic number.

643611011 is a deficient number, since it is larger than the sum of its proper divisors (2504581).

643611011 is a wasteful number, since it uses less digits than its factorization.

643611011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2504580.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 643611011 is about 25369.4897662527. The cubic root of 643611011 is about 863.3916054975.

Adding to 643611011 its reverse (110116346), we get a palindrome (753727357).

The spelling of 643611011 in words is "six hundred forty-three million, six hundred eleven thousand, eleven".