6643221255 has 72 divisors (see below), whose sum is σ = 13093647840. Its totient is φ = 3109814400.

The previous prime is 6643221253. The next prime is 6643221269. The reversal of 6643221255 is 5521223466.

6643221255 is a `hidden beast` number, since 6 + 6 + 432 + 212 + 5 + 5 = 666.

6643221255 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 6643221255 - 2¹ = 6643221253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6643221253) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 136870 + ... + 178940.

It is an arithmetic number, because the mean of its divisors is an integer number (181856220).

Almost surely, 2^6643221255 is an apocalyptic number.

6643221255 is a deficient number, since it is larger than the sum of its proper divisors (6450426585).

6643221255 is a wasteful number, since it uses less digits than its factorization.

6643221255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42133 (or 42119 counting only the distinct ones).

The product of its digits is 86400, while the sum is 36.

The square root of 6643221255 is about 81505.9584018248. The cubic root of 6643221255 is about 1879.8631686100.

The spelling of 6643221255 in words is "six billion, six hundred forty-three million, two hundred twenty-one thousand, two hundred fifty-five".