643487217 has 24 divisors (see below), whose sum is σ = 893691744. Its totient is φ = 411625536.

The previous prime is 643487203. The next prime is 643487227. The reversal of 643487217 is 712784346.

It is a de Polignac number, because none of the positive numbers 2^k-643487217 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643487227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 448333 + ... + 449765.

It is an arithmetic number, because the mean of its divisors is an integer number (37237156).

Almost surely, 2^643487217 is an apocalyptic number.

It is an amenable number.

643487217 is a deficient number, since it is larger than the sum of its proper divisors (250204527).

643487217 is a wasteful number, since it uses less digits than its factorization.

643487217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1597 (or 1538 counting only the distinct ones).

The product of its digits is 225792, while the sum is 42.

The square root of 643487217 is about 25367.0498284684. The cubic root of 643487217 is about 863.3362462033.

The spelling of 643487217 in words is "six hundred forty-three million, four hundred eighty-seven thousand, two hundred seventeen".