643843078 has 4 divisors (see below), whose sum is σ = 965764620. Its totient is φ = 321921538.

The previous prime is 643843073. The next prime is 643843097. The reversal of 643843078 is 870348346.

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 (643843073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160960768 + ... + 160960771.

It is an arithmetic number, because the mean of its divisors is an integer number (241441155).

Almost surely, 2^643843078 is an apocalyptic number.

643843078 is a deficient number, since it is larger than the sum of its proper divisors (321921542).

643843078 is a wasteful number, since it uses less digits than its factorization.

643843078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321921541.

The product of its (nonzero) digits is 387072, while the sum is 43.

The square root of 643843078 is about 25374.0630960042. The cubic root of 643843078 is about 863.4953641442.

The spelling of 643843078 in words is "six hundred forty-three million, eight hundred forty-three thousand, seventy-eight".