643217905 has 8 divisors (see below), whose sum is σ = 842030784. Its totient is φ = 467794800.

The previous prime is 643217873. The next prime is 643217909. The reversal of 643217905 is 509712346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 643217905 - 2⁵ = 643217873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643217909) 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 7 ways as a sum of consecutive naturals, for example, 5847381 + ... + 5847490.

It is an arithmetic number, because the mean of its divisors is an integer number (105253848).

Almost surely, 2^643217905 is an apocalyptic number.

It is an amenable number.

643217905 is a deficient number, since it is larger than the sum of its proper divisors (198812879).

643217905 is a wasteful number, since it uses less digits than its factorization.

643217905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11694887.

The product of its (nonzero) digits is 45360, while the sum is 37.

The square root of 643217905 is about 25361.7409694208. The cubic root of 643217905 is about 863.2157883559.

The spelling of 643217905 in words is "six hundred forty-three million, two hundred seventeen thousand, nine hundred five".