643335265 has 4 divisors (see below), whose sum is σ = 772002324. Its totient is φ = 514668208.

The previous prime is 643335263. The next prime is 643335271. The reversal of 643335265 is 562533346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 562533346 = 2 ⋅281266673.

It can be written as a sum of positive squares in 2 ways, for example, as 180526096 + 462809169 = 13436^2 + 21513^2 .

It is a cyclic number.

It is not a de Polignac number, because 643335265 - 2¹ = 643335263 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643335263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64333522 + ... + 64333531.

It is an arithmetic number, because the mean of its divisors is an integer number (193000581).

Almost surely, 2^643335265 is an apocalyptic number.

It is an amenable number.

643335265 is a deficient number, since it is larger than the sum of its proper divisors (128667059).

643335265 is a wasteful number, since it uses less digits than its factorization.

643335265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128667058.

The product of its digits is 194400, while the sum is 37.

The square root of 643335265 is about 25364.0545851802. The cubic root of 643335265 is about 863.2682852590.

The spelling of 643335265 in words is "six hundred forty-three million, three hundred thirty-five thousand, two hundred sixty-five".