643772217 has 16 divisors (see below), whose sum is σ = 938750400. Its totient is φ = 389184000.

The previous prime is 643772191. The next prime is 643772273. The reversal of 643772217 is 712277346.

It is a de Polignac number, because none of the positive numbers 2^k-643772217 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643772417) 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, 11092 + ... + 37557.

It is an arithmetic number, because the mean of its divisors is an integer number (58671900).

Almost surely, 2^643772217 is an apocalyptic number.

It is an amenable number.

643772217 is a deficient number, since it is larger than the sum of its proper divisors (294978183).

643772217 is a wasteful number, since it uses less digits than its factorization.

643772217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49064.

The product of its digits is 98784, while the sum is 39.

The square root of 643772217 is about 25372.6667301646. Note that the first 3 decimals coincide. The cubic root of 643772217 is about 863.4636843804.

The spelling of 643772217 in words is "six hundred forty-three million, seven hundred seventy-two thousand, two hundred seventeen".