643843211161 has 4 divisors (see below), whose sum is σ = 647944123492. Its totient is φ = 639742298832.

The previous prime is 643843211149. The next prime is 643843211183. The reversal of 643843211161 is 161112348346.

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

It can be written as a sum of positive squares in 2 ways, for example, as 223445290000 + 420397921161 = 472700^2 + 648381^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643843211161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643843311161) 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, 2050455930 + ... + 2050456243.

It is an arithmetic number, because the mean of its divisors is an integer number (161986030873).

Almost surely, 2^643843211161 is an apocalyptic number.

It is an amenable number.

643843211161 is a deficient number, since it is larger than the sum of its proper divisors (4100912331).

643843211161 is a wasteful number, since it uses less digits than its factorization.

643843211161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4100912330.

The product of its digits is 82944, while the sum is 40.

The spelling of 643843211161 in words is "six hundred forty-three billion, eight hundred forty-three million, two hundred eleven thousand, one hundred sixty-one".