221066655809 has 2 divisors, whose sum is σ = 221066655810. Its totient is φ = 221066655808.

The previous prime is 221066655787. The next prime is 221066655811. The reversal of 221066655809 is 908556660122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134084130625 + 86982525184 = 366175^2 + 294928^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221066655809 is a prime.

It is a Sophie Germain prime.

Together with 221066655811, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (221066655829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110533327904 + 110533327905.

It is an arithmetic number, because the mean of its divisors is an integer number (110533327905).

Almost surely, 2^221066655809 is an apocalyptic number.

It is an amenable number.

221066655809 is a deficient number, since it is larger than the sum of its proper divisors (1).

221066655809 is an equidigital number, since it uses as much as digits as its factorization.

221066655809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1555200, while the sum is 50.

The spelling of 221066655809 in words is "two hundred twenty-one billion, sixty-six million, six hundred fifty-five thousand, eight hundred nine".