643786366 has 4 divisors (see below), whose sum is σ = 965679552. Its totient is φ = 321893182.

The previous prime is 643786361. The next prime is 643786417. The reversal of 643786366 is 663687346.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643786361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160946590 + ... + 160946593.

It is an arithmetic number, because the mean of its divisors is an integer number (241419888).

Almost surely, 2^643786366 is an apocalyptic number.

643786366 is a deficient number, since it is larger than the sum of its proper divisors (321893186).

643786366 is a wasteful number, since it uses less digits than its factorization.

643786366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321893185.

The product of its digits is 2612736, while the sum is 49.

The square root of 643786366 is about 25372.9455523004. The cubic root of 643786366 is about 863.4700101469.

The spelling of 643786366 in words is "six hundred forty-three million, seven hundred eighty-six thousand, three hundred sixty-six".