643782879 has 6 divisors (see below), whose sum is σ = 929908616. Its totient is φ = 429188580.

The previous prime is 643782847. The next prime is 643782883. The reversal of 643782879 is 978287346.

It is not a de Polignac number, because 643782879 - 2⁵ = 643782847 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643782899) 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 in 5 ways as a sum of consecutive naturals, for example, 35765707 + ... + 35765724.

Almost surely, 2^643782879 is an apocalyptic number.

643782879 is a deficient number, since it is larger than the sum of its proper divisors (286125737).

643782879 is a wasteful number, since it uses less digits than its factorization.

643782879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71531437 (or 71531434 counting only the distinct ones).

The product of its digits is 4064256, while the sum is 54.

The square root of 643782879 is about 25372.8768372843. The cubic root of 643782879 is about 863.4684511798.

The spelling of 643782879 in words is "six hundred forty-three million, seven hundred eighty-two thousand, eight hundred seventy-nine".