643035641 has 4 divisors (see below), whose sum is σ = 644878500. Its totient is φ = 641192784.

The previous prime is 643035629. The next prime is 643035683. The reversal of 643035641 is 146530346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 146530346 = 2 ⋅73265173.

It can be written as a sum of positive squares in 2 ways, for example, as 329604025 + 313431616 = 18155^2 + 17704^2 .

It is a cyclic number.

It is not a de Polignac number, because 643035641 - 2⁶ = 643035577 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643035598 and 643035607.

It is not an unprimeable number, because it can be changed into a prime (643032641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 920906 + ... + 921603.

It is an arithmetic number, because the mean of its divisors is an integer number (161219625).

Almost surely, 2^643035641 is an apocalyptic number.

It is an amenable number.

643035641 is a deficient number, since it is larger than the sum of its proper divisors (1842859).

643035641 is a wasteful number, since it uses less digits than its factorization.

643035641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1842858.

The product of its (nonzero) digits is 25920, while the sum is 32.

The square root of 643035641 is about 25358.1474283907. The cubic root of 643035641 is about 863.1342462511.

Adding to 643035641 its reverse (146530346), we get a palindrome (789565987).

The spelling of 643035641 in words is "six hundred forty-three million, thirty-five thousand, six hundred forty-one".