643884669 has 12 divisors (see below), whose sum is σ = 932819836. Its totient is φ = 427980672.

The previous prime is 643884629. The next prime is 643884763. The reversal of 643884669 is 966488346.

It can be written as a sum of positive squares in 2 ways, for example, as 294568569 + 349316100 = 17163^2 + 18690^2 .

It is not a de Polignac number, because 643884669 - 2⁸ = 643884413 is a prime.

It is a super-2 number, since 2×643884669² = 829174933946479122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643884629) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 103114 + ... + 109179.

Almost surely, 2^643884669 is an apocalyptic number.

It is an amenable number.

643884669 is a deficient number, since it is larger than the sum of its proper divisors (288935167).

643884669 is a wasteful number, since it uses less digits than its factorization.

643884669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212636 (or 212633 counting only the distinct ones).

The product of its digits is 5971968, while the sum is 54.

The square root of 643884669 is about 25374.8826401227. The cubic root of 643884669 is about 863.5139571128.

The spelling of 643884669 in words is "six hundred forty-three million, eight hundred eighty-four thousand, six hundred sixty-nine".