221066621 has 4 divisors (see below), whose sum is σ = 221888700. Its totient is φ = 220244544.

The previous prime is 221066617. The next prime is 221066627. The reversal of 221066621 is 126660122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 119661721 + 101404900 = 10939^2 + 10070^2 .

It is a cyclic number.

It is not a de Polignac number, because 221066621 - 2² = 221066617 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 (221066627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 410636 + ... + 411173.

It is an arithmetic number, because the mean of its divisors is an integer number (55472175).

Almost surely, 2^221066621 is an apocalyptic number.

It is an amenable number.

221066621 is a deficient number, since it is larger than the sum of its proper divisors (822079).

221066621 is an equidigital number, since it uses as much as digits as its factorization.

221066621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 822078.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 221066621 is about 14868.3092851877. The cubic root of 221066621 is about 604.6551056558.

The spelling of 221066621 in words is "two hundred twenty-one million, sixty-six thousand, six hundred twenty-one".