643405311 has 24 divisors (see below), whose sum is σ = 939170960. Its totient is φ = 424434816.

The previous prime is 643405271. The next prime is 643405331. The reversal of 643405311 is 113504346.

643405311 is a `hidden beast` number, since 6 + 4 + 340 + 5 + 311 = 666.

It is not a de Polignac number, because 643405311 - 2⁷ = 643405183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643405331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 399075 + ... + 400683.

Almost surely, 2^643405311 is an apocalyptic number.

643405311 is a deficient number, since it is larger than the sum of its proper divisors (295765649).

643405311 is a wasteful number, since it uses less digits than its factorization.

643405311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2055 (or 2052 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 643405311 is about 25365.4353599539. The cubic root of 643405311 is about 863.2996148519.

Adding to 643405311 its reverse (113504346), we get a palindrome (756909657).

The spelling of 643405311 in words is "six hundred forty-three million, four hundred five thousand, three hundred eleven".