643111321 has 2 divisors, whose sum is σ = 643111322. Its totient is φ = 643111320.

The previous prime is 643111237. The next prime is 643111327. The reversal of 643111321 is 123111346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 459888025 + 183223296 = 21445^2 + 13536^2 .

It is a cyclic number.

It is not a de Polignac number, because 643111321 - 2¹³ = 643103129 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 643111292 and 643111301.

It is not a weakly prime, because it can be changed into another prime (643111327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321555660 + 321555661.

It is an arithmetic number, because the mean of its divisors is an integer number (321555661).

Almost surely, 2^643111321 is an apocalyptic number.

It is an amenable number.

643111321 is a deficient number, since it is larger than the sum of its proper divisors (1).

643111321 is an equidigital number, since it uses as much as digits as its factorization.

643111321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 22.

The square root of 643111321 is about 25359.6396070607. The cubic root of 643111321 is about 863.1681061872.

Adding to 643111321 its reverse (123111346), we get a palindrome (766222667).

The spelling of 643111321 in words is "six hundred forty-three million, one hundred eleven thousand, three hundred twenty-one".