1661161 has 2 divisors, whose sum is σ = 1661162. Its totient is φ = 1661160.

The previous prime is 1661159. The next prime is 1661173. The reversal of 1661161 is 1611661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1142761 + 518400 = 1069^2 + 720^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661161 - 2¹ = 1661159 is a prime.

Together with 1661159, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1661111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830580 + 830581.

It is an arithmetic number, because the mean of its divisors is an integer number (830581).

2^1661161 is an apocalyptic number.

It is an amenable number.

1661161 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661161 is an equidigital number, since it uses as much as digits as its factorization.

1661161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 216, while the sum is 22.

The square root of 1661161 is about 1288.8603493009. The cubic root of 1661161 is about 118.4324123354.

The spelling of 1661161 in words is "one million, six hundred sixty-one thousand, one hundred sixty-one".