1661605171 has 2 divisors, whose sum is σ = 1661605172. Its totient is φ = 1661605170.

The previous prime is 1661605151. The next prime is 1661605181. The reversal of 1661605171 is 1715061661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1661605171 - 2¹⁵ = 1661572403 is a prime.

It is not a weakly prime, because it can be changed into another prime (1661605111) 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, 830802585 + 830802586.

It is an arithmetic number, because the mean of its divisors is an integer number (830802586).

Almost surely, 2^1661605171 is an apocalyptic number.

1661605171 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661605171 is an equidigital number, since it uses as much as digits as its factorization.

1661605171 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 34.

The square root of 1661605171 is about 40762.7915015643. The cubic root of 1661605171 is about 1184.4296711312.

The spelling of 1661605171 in words is "one billion, six hundred sixty-one million, six hundred five thousand, one hundred seventy-one".