643876369 has 4 divisors (see below), whose sum is σ = 645933796. Its totient is φ = 641818944.

The previous prime is 643876361. The next prime is 643876391. The reversal of 643876369 is 963678346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 106193025 + 537683344 = 10305^2 + 23188^2 .

It is a cyclic number.

It is not a de Polignac number, because 643876369 - 2³ = 643876361 is a prime.

It is a super-2 number, since 2×643876369² = 829153557113248322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643876361) 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, 1028244 + ... + 1028869.

It is an arithmetic number, because the mean of its divisors is an integer number (161483449).

Almost surely, 2^643876369 is an apocalyptic number.

It is an amenable number.

643876369 is a deficient number, since it is larger than the sum of its proper divisors (2057427).

643876369 is a wasteful number, since it uses less digits than its factorization.

643876369 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2057426.

The product of its digits is 3919104, while the sum is 52.

The square root of 643876369 is about 25374.7190920412. The cubic root of 643876369 is about 863.5102467193.

It can be divided in two parts, 64387 and 6369, that added together give a square (70756 = 266²).

The spelling of 643876369 in words is "six hundred forty-three million, eight hundred seventy-six thousand, three hundred sixty-nine".