1666161617 has 2 divisors, whose sum is σ = 1666161618. Its totient is φ = 1666161616.

The previous prime is 1666161599. The next prime is 1666161631. The reversal of 1666161617 is 7161616661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1054885441 + 611276176 = 32479^2 + 24724^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666161617 - 2¹⁴ = 1666145233 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666161667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833080808 + 833080809.

It is an arithmetic number, because the mean of its divisors is an integer number (833080809).

Almost surely, 2^1666161617 is an apocalyptic number.

It is an amenable number.

1666161617 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666161617 is an equidigital number, since it uses as much as digits as its factorization.

1666161617 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 41.

The square root of 1666161617 is about 40818.6430078218. The cubic root of 1666161617 is about 1185.5113288791.

The spelling of 1666161617 in words is "one billion, six hundred sixty-six million, one hundred sixty-one thousand, six hundred seventeen".