643605985 has 8 divisors (see below), whose sum is σ = 842538816. Its totient is φ = 468077040.

The previous prime is 643605979. The next prime is 643606003. The reversal of 643605985 is 589506346.

643605985 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 643605985 - 2¹⁷ = 643474913 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5850909 + ... + 5851018.

It is an arithmetic number, because the mean of its divisors is an integer number (105317352).

Almost surely, 2^643605985 is an apocalyptic number.

It is an amenable number.

643605985 is a deficient number, since it is larger than the sum of its proper divisors (198932831).

643605985 is a wasteful number, since it uses less digits than its factorization.

643605985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11701943.

The product of its (nonzero) digits is 777600, while the sum is 46.

The square root of 643605985 is about 25369.3907100663. The cubic root of 643605985 is about 863.3893580646.

The spelling of 643605985 in words is "six hundred forty-three million, six hundred five thousand, nine hundred eighty-five".