643860239831 has 4 divisors (see below), whose sum is σ = 643957521000. Its totient is φ = 643762958664.

The previous prime is 643860239819. The next prime is 643860239837. The reversal of 643860239831 is 138932068346.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 138932068346 = 2 ⋅69466034173.

It is a cyclic number.

It is not a de Polignac number, because 643860239831 - 2¹⁰ = 643860238807 is a prime.

It is a super-2 number, since 2×643860239831² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643860239837) 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 3 ways as a sum of consecutive naturals, for example, 48630656 + ... + 48643893.

It is an arithmetic number, because the mean of its divisors is an integer number (160989380250).

Almost surely, 2^643860239831 is an apocalyptic number.

643860239831 is a deficient number, since it is larger than the sum of its proper divisors (97281169).

643860239831 is an equidigital number, since it uses as much as digits as its factorization.

643860239831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97281168.

The product of its (nonzero) digits is 4478976, while the sum is 53.

The spelling of 643860239831 in words is "six hundred forty-three billion, eight hundred sixty million, two hundred thirty-nine thousand, eight hundred thirty-one".