643899217 has 16 divisors (see below), whose sum is σ = 704471040. Its totient is φ = 584955072.

The previous prime is 643899187. The next prime is 643899229. The reversal of 643899217 is 712998346.

It is a de Polignac number, because none of the positive numbers 2^k-643899217 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643899287) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 392523 + ... + 394159.

It is an arithmetic number, because the mean of its divisors is an integer number (44029440).

Almost surely, 2^643899217 is an apocalyptic number.

It is an amenable number.

643899217 is a deficient number, since it is larger than the sum of its proper divisors (60571823).

643899217 is a wasteful number, since it uses less digits than its factorization.

643899217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2112.

The product of its digits is 653184, while the sum is 49.

The square root of 643899217 is about 25375.1692999278. The cubic root of 643899217 is about 863.5204605065.

The spelling of 643899217 in words is "six hundred forty-three million, eight hundred ninety-nine thousand, two hundred seventeen".