643850555 has 4 divisors (see below), whose sum is σ = 772620672. Its totient is φ = 515080440.

The previous prime is 643850533. The next prime is 643850573. The reversal of 643850555 is 555058346.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 643850555 - 2⁶ = 643850491 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64385051 + ... + 64385060.

It is an arithmetic number, because the mean of its divisors is an integer number (193155168).

Almost surely, 2^643850555 is an apocalyptic number.

643850555 is a deficient number, since it is larger than the sum of its proper divisors (128770117).

643850555 is a wasteful number, since it uses less digits than its factorization.

643850555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128770116.

The product of its (nonzero) digits is 360000, while the sum is 41.

The square root of 643850555 is about 25374.2104310656. The cubic root of 643850555 is about 863.4987067444.

The spelling of 643850555 in words is "six hundred forty-three million, eight hundred fifty thousand, five hundred fifty-five".