2166645491 has 2 divisors, whose sum is σ = 2166645492. Its totient is φ = 2166645490.

The previous prime is 2166645431. The next prime is 2166645497. The reversal of 2166645491 is 1945466612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2166645491 - 2¹⁸ = 2166383347 is a prime.

It is not a weakly prime, because it can be changed into another prime (2166645497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1083322745 + 1083322746.

It is an arithmetic number, because the mean of its divisors is an integer number (1083322746).

Almost surely, 2^2166645491 is an apocalyptic number.

2166645491 is a deficient number, since it is larger than the sum of its proper divisors (1).

2166645491 is an equidigital number, since it uses as much as digits as its factorization.

2166645491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 44.

The square root of 2166645491 is about 46547.2393488593. The cubic root of 2166645491 is about 1293.9851305438.

The spelling of 2166645491 in words is "two billion, one hundred sixty-six million, six hundred forty-five thousand, four hundred ninety-one".