643523641 has 2 divisors, whose sum is σ = 643523642. Its totient is φ = 643523640.

The previous prime is 643523633. The next prime is 643523687. The reversal of 643523641 is 146325346.

643523641 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 383024041 + 260499600 = 19571^2 + 16140^2 .

It is a cyclic number.

It is not a de Polignac number, because 643523641 - 2³ = 643523633 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643523597 and 643523606.

It is not a weakly prime, because it can be changed into another prime (643523611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321761820 + 321761821.

It is an arithmetic number, because the mean of its divisors is an integer number (321761821).

Almost surely, 2^643523641 is an apocalyptic number.

It is an amenable number.

643523641 is a deficient number, since it is larger than the sum of its proper divisors (1).

643523641 is an equidigital number, since it uses as much as digits as its factorization.

643523641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 34.

The square root of 643523641 is about 25367.7677575304. The cubic root of 643523641 is about 863.3525353464.

Adding to 643523641 its reverse (146325346), we get a palindrome (789848987).

The spelling of 643523641 in words is "six hundred forty-three million, five hundred twenty-three thousand, six hundred forty-one".