1661126161 has 4 divisors (see below), whose sum is σ = 1667037924. Its totient is φ = 1655214400.

The previous prime is 1661126149. The next prime is 1661126189. The reversal of 1661126161 is 1616211661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 728190225 + 932935936 = 26985^2 + 30544^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661126161 - 2⁹ = 1661125649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661426161) 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 in 3 ways as a sum of consecutive naturals, for example, 2955460 + ... + 2956021.

It is an arithmetic number, because the mean of its divisors is an integer number (416759481).

Almost surely, 2^1661126161 is an apocalyptic number.

It is an amenable number.

1661126161 is a deficient number, since it is larger than the sum of its proper divisors (5911763).

1661126161 is an equidigital number, since it uses as much as digits as its factorization.

1661126161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5911762.

The product of its digits is 2592, while the sum is 31.

The square root of 1661126161 is about 40756.9154990905. The cubic root of 1661126161 is about 1184.3158438124.

The spelling of 1661126161 in words is "one billion, six hundred sixty-one million, one hundred twenty-six thousand, one hundred sixty-one".