221666106434491 has 2 divisors, whose sum is σ = 221666106434492. Its totient is φ = 221666106434490.

The previous prime is 221666106434447. The next prime is 221666106434533. The reversal of 221666106434491 is 194434601666122.

It is a happy number.

221666106434491 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 is a cyclic number.

It is not a de Polignac number, because 221666106434491 - 2¹⁵ = 221666106401723 is a prime.

It is not a weakly prime, because it can be changed into another prime (221666116434491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110833053217245 + 110833053217246.

It is an arithmetic number, because the mean of its divisors is an integer number (110833053217246).

Almost surely, 2^{221666106434491} is an apocalyptic number.

221666106434491 is a deficient number, since it is larger than the sum of its proper divisors (1).

221666106434491 is an equidigital number, since it uses as much as digits as its factorization.

221666106434491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8957952, while the sum is 55.

The spelling of 221666106434491 in words is "two hundred twenty-one trillion, six hundred sixty-six billion, one hundred six million, four hundred thirty-four thousand, four hundred ninety-one".