643121 has 2 divisors, whose sum is σ = 643122. Its totient is φ = 643120.

The previous prime is 643099. The next prime is 643129. The reversal of 643121 is 121346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 616225 + 26896 = 785^2 + 164^2 .

It is a cyclic number.

It is not a de Polignac number, because 643121 - 2¹⁸ = 380977 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643121.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643121.

It is not a weakly prime, because it can be changed into another prime (643129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321560 + 321561.

It is an arithmetic number, because the mean of its divisors is an integer number (321561).

2⁶⁴³¹²¹ is an apocalyptic number.

It is an amenable number.

643121 is a deficient number, since it is larger than the sum of its proper divisors (1).

643121 is an equidigital number, since it uses as much as digits as its factorization.

643121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 144, while the sum is 17.

The square root of 643121 is about 801.9482526946. The cubic root of 643121 is about 86.3172436470.

Adding to 643121 its reverse (121346), we get a palindrome (764467).

The spelling of 643121 in words is "six hundred forty-three thousand, one hundred twenty-one".