643311421 has 4 divisors (see below), whose sum is σ = 652913152. Its totient is φ = 633709692.

The previous prime is 643311407. The next prime is 643311463. The reversal of 643311421 is 124113346.

643311421 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 643311421 - 2⁹ = 643310909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643314421) 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, 4800765 + ... + 4800898.

It is an arithmetic number, because the mean of its divisors is an integer number (163228288).

Almost surely, 2^643311421 is an apocalyptic number.

It is an amenable number.

643311421 is a deficient number, since it is larger than the sum of its proper divisors (9601731).

643311421 is an equidigital number, since it uses as much as digits as its factorization.

643311421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9601730.

The product of its digits is 1728, while the sum is 25.

The square root of 643311421 is about 25363.5845455645. The cubic root of 643311421 is about 863.2576199940.

Adding to 643311421 its reverse (124113346), we get a palindrome (767424767).

The spelling of 643311421 in words is "six hundred forty-three million, three hundred eleven thousand, four hundred twenty-one".