643716166 has 4 divisors (see below), whose sum is σ = 965574252. Its totient is φ = 321858082.

The previous prime is 643716163. The next prime is 643716167. The reversal of 643716166 is 661617346.

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

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643716163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160929040 + ... + 160929043.

It is an arithmetic number, because the mean of its divisors is an integer number (241393563).

Almost surely, 2^643716166 is an apocalyptic number.

643716166 is a deficient number, since it is larger than the sum of its proper divisors (321858086).

643716166 is a wasteful number, since it uses less digits than its factorization.

643716166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321858085.

The product of its digits is 108864, while the sum is 40.

The square root of 643716166 is about 25371.5621513536. The cubic root of 643716166 is about 863.4386240634.

The spelling of 643716166 in words is "six hundred forty-three million, seven hundred sixteen thousand, one hundred sixty-six".