643665120053 has 4 divisors (see below), whose sum is σ = 643666815648. Its totient is φ = 643663424460.

The previous prime is 643665120047. The next prime is 643665120103. The reversal of 643665120053 is 350021566346.

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 643665120053 - 2¹⁰ = 643665119029 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643665420053) 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, 12848 + ... + 1134678.

It is an arithmetic number, because the mean of its divisors is an integer number (160916703912).

Almost surely, 2^643665120053 is an apocalyptic number.

It is an amenable number.

643665120053 is a deficient number, since it is larger than the sum of its proper divisors (1695595).

643665120053 is a wasteful number, since it uses less digits than its factorization.

643665120053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1695594.

The product of its (nonzero) digits is 388800, while the sum is 41.

Adding to 643665120053 its reverse (350021566346), we get a palindrome (993686686399).

The spelling of 643665120053 in words is "six hundred forty-three billion, six hundred sixty-five million, one hundred twenty thousand, fifty-three".