643354778 has 16 divisors (see below), whose sum is σ = 1054027296. Its totient is φ = 292082640.

The previous prime is 643354771. The next prime is 643354793. The reversal of 643354778 is 877453346.

It is not an unprimeable number, because it can be changed into a prime (643354771) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1625 + ... + 35907.

It is an arithmetic number, because the mean of its divisors is an integer number (65876706).

Almost surely, 2^643354778 is an apocalyptic number.

643354778 is a deficient number, since it is larger than the sum of its proper divisors (410672518).

643354778 is a wasteful number, since it uses less digits than its factorization.

643354778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35149.

The product of its digits is 1693440, while the sum is 47.

The square root of 643354778 is about 25364.4392407954. The cubic root of 643354778 is about 863.2770131001.

The spelling of 643354778 in words is "six hundred forty-three million, three hundred fifty-four thousand, seven hundred seventy-eight".