643541643 has 12 divisors (see below), whose sum is σ = 944799648. Its totient is φ = 421994160.

The previous prime is 643541641. The next prime is 643541659. The reversal of 643541643 is 346145346.

643541643 is a `hidden beast` number, since 6 + 4 + 3 + 5 + 4 + 1 + 643 = 666.

It is not a de Polignac number, because 643541643 - 2¹ = 643541641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643541598 and 643541607.

It is not an unprimeable number, because it can be changed into a prime (643541641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 585555 + ... + 586652.

It is an arithmetic number, because the mean of its divisors is an integer number (78733304).

Almost surely, 2^643541643 is an apocalyptic number.

643541643 is a deficient number, since it is larger than the sum of its proper divisors (301258005).

643541643 is a wasteful number, since it uses less digits than its factorization.

643541643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1172274 (or 1172271 counting only the distinct ones).

The product of its digits is 103680, while the sum is 36.

The square root of 643541643 is about 25368.1225753898. The cubic root of 643541643 is about 863.3605857771.

Adding to 643541643 its reverse (346145346), we get a palindrome (989686989).

The spelling of 643541643 in words is "six hundred forty-three million, five hundred forty-one thousand, six hundred forty-three".