643999844077 has 4 divisors (see below), whose sum is σ = 644009352480. Its totient is φ = 643990335676.

The previous prime is 643999844071. The next prime is 643999844149. The reversal of 643999844077 is 770448999346.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 643999844077 - 2³⁵ = 609640105709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643999843997 and 643999844015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643999844071) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4651873 + ... + 4788310.

It is an arithmetic number, because the mean of its divisors is an integer number (161002338120).

Almost surely, 2^643999844077 is an apocalyptic number.

It is an amenable number.

643999844077 is a deficient number, since it is larger than the sum of its proper divisors (9508403).

643999844077 is an equidigital number, since it uses as much as digits as its factorization.

643999844077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9508402.

The product of its (nonzero) digits is 329204736, while the sum is 70.

The spelling of 643999844077 in words is "six hundred forty-three billion, nine hundred ninety-nine million, eight hundred forty-four thousand, seventy-seven".