221066509 has 2 divisors, whose sum is σ = 221066510. Its totient is φ = 221066508.

The previous prime is 221066473. The next prime is 221066537. The reversal of 221066509 is 905660122.

221066509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 210685225 + 10381284 = 14515^2 + 3222^2 .

It is a cyclic number.

It is not a de Polignac number, because 221066509 - 2⁹ = 221065997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221066309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110533254 + 110533255.

It is an arithmetic number, because the mean of its divisors is an integer number (110533255).

Almost surely, 2^221066509 is an apocalyptic number.

It is an amenable number.

221066509 is a deficient number, since it is larger than the sum of its proper divisors (1).

221066509 is an equidigital number, since it uses as much as digits as its factorization.

221066509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 221066509 is about 14868.3055187873. The cubic root of 221066509 is about 604.6550035427.

The spelling of 221066509 in words is "two hundred twenty-one million, sixty-six thousand, five hundred nine".