643821387887 has 16 divisors (see below), whose sum is σ = 667878614304. Its totient is φ = 620116560000.

The previous prime is 643821387863. The next prime is 643821387901. The reversal of 643821387887 is 788783128346.

It is a cyclic number.

It is not a de Polignac number, because 643821387887 - 2¹⁴ = 643821371503 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 (643821387487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32954312 + ... + 32973842.

It is an arithmetic number, because the mean of its divisors is an integer number (41742413394).

Almost surely, 2^643821387887 is an apocalyptic number.

643821387887 is a deficient number, since it is larger than the sum of its proper divisors (24057226417).

643821387887 is a wasteful number, since it uses less digits than its factorization.

643821387887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28490.

The product of its digits is 86704128, while the sum is 65.

The spelling of 643821387887 in words is "six hundred forty-three billion, eight hundred twenty-one million, three hundred eighty-seven thousand, eight hundred eighty-seven".