221966545781 has 2 divisors, whose sum is σ = 221966545782. Its totient is φ = 221966545780.

The previous prime is 221966545753. The next prime is 221966545807. The reversal of 221966545781 is 187545669122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 154712422225 + 67254123556 = 393335^2 + 259334^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221966545781 is a prime.

It is a super-2 number, since 2×221966545781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221968545781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110983272890 + 110983272891.

It is an arithmetic number, because the mean of its divisors is an integer number (110983272891).

Almost surely, 2^221966545781 is an apocalyptic number.

It is an amenable number.

221966545781 is a deficient number, since it is larger than the sum of its proper divisors (1).

221966545781 is an equidigital number, since it uses as much as digits as its factorization.

221966545781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7257600, while the sum is 56.

The spelling of 221966545781 in words is "two hundred twenty-one billion, nine hundred sixty-six million, five hundred forty-five thousand, seven hundred eighty-one".