6643450561 has 16 divisors (see below), whose sum is σ = 7325225280. Its totient is φ = 5974804480.

The previous prime is 6643450549. The next prime is 6643450577. The reversal of 6643450561 is 1650543466.

It is a cyclic number.

It is not a de Polignac number, because 6643450561 - 2¹⁵ = 6643417793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6643450591) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 948705 + ... + 955681.

It is an arithmetic number, because the mean of its divisors is an integer number (457826580).

Almost surely, 2^6643450561 is an apocalyptic number.

It is an amenable number.

6643450561 is a deficient number, since it is larger than the sum of its proper divisors (681774719).

6643450561 is a wasteful number, since it uses less digits than its factorization.

6643450561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7904.

The product of its (nonzero) digits is 259200, while the sum is 40.

The square root of 6643450561 is about 81507.3650721209. The cubic root of 6643450561 is about 1879.8847976224.

The spelling of 6643450561 in words is "six billion, six hundred forty-three million, four hundred fifty thousand, five hundred sixty-one".