643105331021 has 2 divisors, whose sum is σ = 643105331022. Its totient is φ = 643105331020.

The previous prime is 643105331017. The next prime is 643105331059. The reversal of 643105331021 is 120133501346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 522744906121 + 120360424900 = 723011^2 + 346930^2 .

It is a cyclic number.

It is not a de Polignac number, because 643105331021 - 2² = 643105331017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643105331221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321552665510 + 321552665511.

It is an arithmetic number, because the mean of its divisors is an integer number (321552665511).

Almost surely, 2^643105331021 is an apocalyptic number.

It is an amenable number.

643105331021 is a deficient number, since it is larger than the sum of its proper divisors (1).

643105331021 is an equidigital number, since it uses as much as digits as its factorization.

643105331021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 29.

Adding to 643105331021 its reverse (120133501346), we get a palindrome (763238832367).

The spelling of 643105331021 in words is "six hundred forty-three billion, one hundred five million, three hundred thirty-one thousand, twenty-one".