6655221 has 6 divisors (see below), whose sum is σ = 9613110. Its totient is φ = 4436808.

The previous prime is 6655199. The next prime is 6655237. The reversal of 6655221 is 1225566.

6655221 is a `hidden beast` number, since 6 + 655 + 2 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 3802500 + 2852721 = 1950^2 + 1689^2 .

It is not a de Polignac number, because 6655221 - 2⁷ = 6655093 is a prime.

It is a Curzon number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6655261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 369726 + ... + 369743.

It is an arithmetic number, because the mean of its divisors is an integer number (1602185).

Almost surely, 2^6655221 is an apocalyptic number.

It is an amenable number.

6655221 is a deficient number, since it is larger than the sum of its proper divisors (2957889).

6655221 is a wasteful number, since it uses less digits than its factorization.

6655221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 739475 (or 739472 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 6655221 is about 2579.7715015094. The cubic root of 6655221 is about 188.0994362309.

It can be divided in two parts, 665 and 5221, that added together give a triangular number (5886 = T₁₀₈).

The spelling of 6655221 in words is "six million, six hundred fifty-five thousand, two hundred twenty-one".