6645363689 has 4 divisors (see below), whose sum is σ = 6645527040. Its totient is φ = 6645200340.

The previous prime is 6645363671. The next prime is 6645363761. The reversal of 6645363689 is 9863635466.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9863635466 = 2 ⋅4931817733.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6645363689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6645363629) 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, 33272 + ... + 119990.

It is an arithmetic number, because the mean of its divisors is an integer number (1661381760).

Almost surely, 2^6645363689 is an apocalyptic number.

It is an amenable number.

6645363689 is a deficient number, since it is larger than the sum of its proper divisors (163351).

6645363689 is an equidigital number, since it uses as much as digits as its factorization.

6645363689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163350.

The product of its digits is 16796160, while the sum is 56.

The square root of 6645363689 is about 81519.1001483701. The cubic root of 6645363689 is about 1880.0652317225.

The spelling of 6645363689 in words is "six billion, six hundred forty-five million, three hundred sixty-three thousand, six hundred eighty-nine".