1661161611 has 4 divisors (see below), whose sum is σ = 2214882152. Its totient is φ = 1107441072.

The previous prime is 1661161597. The next prime is 1661161643. The reversal of 1661161611 is 1161611661.

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

It is not a de Polignac number, because 1661161611 - 2³⁰ = 587419787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661163611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 276860266 + ... + 276860271.

It is an arithmetic number, because the mean of its divisors is an integer number (553720538).

Almost surely, 2^1661161611 is an apocalyptic number.

1661161611 is a deficient number, since it is larger than the sum of its proper divisors (553720541).

1661161611 is an equidigital number, since it uses as much as digits as its factorization.

1661161611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 553720540.

The product of its digits is 1296, while the sum is 30.

The square root of 1661161611 is about 40757.3503922912. The cubic root of 1661161611 is about 1184.3242685584.

The spelling of 1661161611 in words is "one billion, six hundred sixty-one million, one hundred sixty-one thousand, six hundred eleven".