643679194 has 16 divisors (see below), whose sum is σ = 1044067968. Its totient is φ = 296462272.

The previous prime is 643679191. The next prime is 643679227. The reversal of 643679194 is 491976346.

It is not an unprimeable number, because it can be changed into a prime (643679191) 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, 199804 + ... + 202999.

It is an arithmetic number, because the mean of its divisors is an integer number (65254248).

Almost surely, 2^643679194 is an apocalyptic number.

643679194 is a deficient number, since it is larger than the sum of its proper divisors (400388774).

643679194 is a wasteful number, since it uses less digits than its factorization.

643679194 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402869.

The product of its digits is 979776, while the sum is 49.

The square root of 643679194 is about 25370.8335298626. The cubic root of 643679194 is about 863.4220931420.

The spelling of 643679194 in words is "six hundred forty-three million, six hundred seventy-nine thousand, one hundred ninety-four".