1661023511 has 6 divisors (see below), whose sum is σ = 1932211080. Its totient is φ = 1423734396.

The previous prime is 1661023501. The next prime is 1661023513. The reversal of 1661023511 is 1153201661.

It is not a de Polignac number, because 1661023511 - 2³⁰ = 587281687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661023513) 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 in 5 ways as a sum of consecutive naturals, for example, 16949171 + ... + 16949268.

It is an arithmetic number, because the mean of its divisors is an integer number (322035180).

Almost surely, 2^1661023511 is an apocalyptic number.

1661023511 is a deficient number, since it is larger than the sum of its proper divisors (271187569).

1661023511 is an equidigital number, since it uses as much as digits as its factorization.

1661023511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33898453 (or 33898446 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 1661023511 is about 40755.6561841421. The cubic root of 1661023511 is about 1184.2914482089.

The spelling of 1661023511 in words is "one billion, six hundred sixty-one million, twenty-three thousand, five hundred eleven".