643165405 has 24 divisors (see below), whose sum is σ = 801829368. Its totient is φ = 495161856.

The previous prime is 643165381. The next prime is 643165417. The reversal of 643165405 is 504561346.

It can be written as a sum of positive squares in 4 ways, for example, as 61246276 + 581919129 = 7826^2 + 24123^2 .

It is a de Polignac number, because none of the positive numbers 2^k-643165405 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 674409 + ... + 675361.

It is an arithmetic number, because the mean of its divisors is an integer number (33409557).

Almost surely, 2^643165405 is an apocalyptic number.

It is an amenable number.

643165405 is a deficient number, since it is larger than the sum of its proper divisors (158663963).

643165405 is an equidigital number, since it uses as much as digits as its factorization.

643165405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1117 (or 1074 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 643165405 is about 25360.7059247175. The cubic root of 643165405 is about 863.1923022446.

The spelling of 643165405 in words is "six hundred forty-three million, one hundred sixty-five thousand, four hundred five".