643321829831381 has 2 divisors, whose sum is σ = 643321829831382. Its totient is φ = 643321829831380.

The previous prime is 643321829831347. The next prime is 643321829831407. The reversal of 643321829831381 is 183138928123346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 406149817679281 + 237172012152100 = 20153159^2 + 15400390^2 .

It is a cyclic number.

It is not a de Polignac number, because 643321829831381 - 2¹⁴ = 643321829814997 is a prime.

It is a super-2 number, since 2×643321829831381² (a number of 30 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643321829831341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321660914915690 + 321660914915691.

It is an arithmetic number, because the mean of its divisors is an integer number (321660914915691).

Almost surely, 2^{643321829831381} is an apocalyptic number.

It is an amenable number.

643321829831381 is a deficient number, since it is larger than the sum of its proper divisors (1).

643321829831381 is an equidigital number, since it uses as much as digits as its factorization.

643321829831381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35831808, while the sum is 62.

The spelling of 643321829831381 in words is "six hundred forty-three trillion, three hundred twenty-one billion, eight hundred twenty-nine million, eight hundred thirty-one thousand, three hundred eighty-one".