166442561 has 2 divisors, whose sum is σ = 166442562. Its totient is φ = 166442560.

The previous prime is 166442501. The next prime is 166442567. The reversal of 166442561 is 165244661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 165379600 + 1062961 = 12860^2 + 1031^2 .

It is an emirp because it is prime and its reverse (165244661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166442561 - 2¹⁴ = 166426177 is a prime.

It is a super-2 number, since 2×166442561² = 55406252224477442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (166442567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83221280 + 83221281.

It is an arithmetic number, because the mean of its divisors is an integer number (83221281).

Almost surely, 2^166442561 is an apocalyptic number.

It is an amenable number.

166442561 is a deficient number, since it is larger than the sum of its proper divisors (1).

166442561 is an equidigital number, since it uses as much as digits as its factorization.

166442561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34560, while the sum is 35.

The square root of 166442561 is about 12901.2619925339. The cubic root of 166442561 is about 550.0744373081.

The spelling of 166442561 in words is "one hundred sixty-six million, four hundred forty-two thousand, five hundred sixty-one".