643918941 has 24 divisors (see below), whose sum is σ = 952258944. Its totient is φ = 419100480.

The previous prime is 643918939. The next prime is 643918963. The reversal of 643918941 is 149819346.

643918941 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 643918941 - 2¹ = 643918939 is a prime.

It is a super-2 number, since 2×643918941² = 829263205157122962, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643918921) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 191646 + ... + 194976.

It is an arithmetic number, because the mean of its divisors is an integer number (39677456).

Almost surely, 2^643918941 is an apocalyptic number.

It is an amenable number.

643918941 is a deficient number, since it is larger than the sum of its proper divisors (308340003).

643918941 is a wasteful number, since it uses less digits than its factorization.

643918941 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3841 (or 3838 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 643918941 is about 25375.5579446049. The cubic root of 643918941 is about 863.5292775715.

The spelling of 643918941 in words is "six hundred forty-three million, nine hundred eighteen thousand, nine hundred forty-one".